diff --git a/source/app.d b/source/app.d
index 20cdafd..9466856 100644
--- a/source/app.d
+++ b/source/app.d
@@ -1,7 +1,7 @@
 import std.stdio;
 
-import day9.part1;
+import day10.part1;
 
 void main() {
-	lavaTubes();
+	syntaxChecker();
 }
diff --git a/source/day10/input.txt b/source/day10/input.txt
new file mode 100644
index 0000000..214cf11
--- /dev/null
+++ b/source/day10/input.txt
@@ -0,0 +1,94 @@
+{{<{{{{([{[([[()<>]{<>{}}]<([]())(()<>)>)((({}())[()[]])<<[][]>[{}[]]>)]{{(<{}<>>{<><>}]([<>[]]<
+[(<{{[{(<({{<<[]()><<>{}>>([<>[]]{<><>})}})>)}]}}>[{(<{({[{[[({}())((){})]({{}[]})]<<[<>{}]([][])>({<>()}
+(({<{[{({(([[([]())({}())]]({[[]{}]([][]))<((){})<{}<>>>))[(([<>[]]<[]>)(([]{}){{}{}}))])})[({<[{
+([{{[([<({<<<([]())[()[]]>{<()[]>[[]()]}>[{<[]{}><[]>>{<<>()>{[]()}}]>[[[[[]{}]([]<>)]<{<>{}}
+[[((<({<(<{<<{{}()}{[][]}>[((){})]>}>{((<({}<>)<{}()>>[[<>()]])<<<[][]><<>[]>>{<{}[]>(<>())}>)<{[[{
+[{<{{{{<([{[(<[]<>>(<>[])){({}<>)([]<>)}]{{([][])[<>{}]}{<[]<>>(<>{})}}}])<<{[<[<>{}]<(){}>>{<{}<>><<>
+(({({([(<[[([[{}{}]([]<>}][(<>()){(){}}])]](({{{{}<>}<{}[]>}([{}[]][(){}])}[(<[]{}>({}()))<<<><>>>])<[{
+[{<((<{(<{<<{[()()](()<>)}<({}[])([]<>)>>{(<<><>>[[]{}])[[[]()](<>[])]}>{[[({}<>)([]<>)][[{}[]
+{<{<{{(<[[{[[({}[])[()[]]]([()<>][{}[]])]<<({}())[{}{}]><[<>[]](<><>)>>}(([([]{})((){})]((<>)([]{}))))]<{<<<
+<{(<<(<[<{<[{[<>[]][{}{}]}{{()<>}{<><>}>]>[<(([]{})[[]])>]}<[<([{}{}][<><>]){([]{})}>]({<{<>()}>{
+{[[<{{{<<<[<((()<>)({}{}))<{{}()}>>]<((([]{}){{}<>})[{{}<>}([]{})])({{()[]}[[]()]}[{{}()}({
+<[[[{{([{[({[<{}[]>[{}()]]{<()>}}({<()()>}<<<>()>{[]}>))]((({({}[])>{[(){}]{<><>}})(({()[]}[()<>]
+[([([([<[{{<[[{}[]]{<>{}}][<{}>(()[])]>[({<>()}(()[])){<[][]>{()[]}}]}}<{(({()}([]()))(([]())<()[]>))<((<>{}
+<{[{(({([([[{((){})[[]]>{{{}[]}[<>()]}]])]{([([<[]{}>((){})]<[()<>]<()()>>)][<<{<>{}}{<><>
+[[{{(([{(({[[{{}[]}]][<<<>()>({}{})>[[{}<>]{{}<>}]]}[(({{}}{[][]}){[{}{}][<>[]]})(<<<>{}><<><>>>)])<[
+[[{([<<([[<(<{<>()}<[][]>>{[<>[]]{()[]}}){[<[][]><{}()>][([]())<<><>>]}>]((<<[(){}][(){}]><([])>>))
+[{[<{(([(([([(<>[]}(<>{})][<{}[]>[()[]]])<{[{}<>]<[]<>>}{{[]<>}{{}{}}}>]<<{[<>{}](<>())}{{()[]}{<>{}}}>[
+{({<[(((<{<<[[()<>]]<({}<>)>>>[<({[]<>}{()<>})[[()<>][<><>]]>({[{}[]]({}<>)}[<(){}>(<>())])]}><[{<[[<>
+<(((({{(<({[<<[]<>>>([()()]{<>()})][<[{}{}]{<>()}>{{{}{}}[[][]]}]}{(<<<><>>(()<>)>(<<>()>[()[]]))
+[<{{[{[[[<(({<()()>[(){}]}[([]())[(){}]]))>{[<[[[]]<[][]>]{[[][]](()())}>[(<<>()>{[]<>})(({}())<{}[]>)
+(<[[((<<({[(([()[]]([]<>)){{(){}}})]{<(<<><>><[]{}>)<<{}<>]([]<>)>>}}){(<{<{[]{}}[{}<>]>}>{({(<><>)<()[]>}{((
+{[{((<{<<<<([<[]{}>[[][]]]<[[]()][<>[]]>)[[<{}[]>{{}()}](<()<>>[<>[]])]>>[{([<()[]>{{}[]}](({}{}
+(<([<((<{[<<(((){})<<><>>)<[{}()]<[]<>>}>[([[]{}](()[]))]>[<{({}()){{}()}}>[(([]<>)({}[])){
+{((((<(({[(<{<()]([][])}>){[<[[][]]>]<{{{}<>}[[][]]}>}]}[<{([{[]{}}]{[(){}]<<>()>})[(<()<>>{()<>
+<<{([{<[[[<{([[]<>]){[<>()][(){}]}}[{(()[])[()[]]}]>][{{[{{}[]}<()<>>]>[[{(){}}[<>[]]][[<>[]]({}()
+<((<[<(([<[{({<><>}(()[]))}]<[<[{}()]<()[]>>(<()()>)][[(<>())<()())]<{<>}<{}>>]>>({{<<<>[]><<>(
+[({{{{{{(([[<<()()><<>[]>>[{[]<>}]]{(<{}<>>(()[]))<<[][]>(()())>}]([<({}()><[][]>>]<{[[][]]<[]<>>}(
+(<(<{{<[{{{[<[<>[]]<[]{}>>[{<>{}}{()()}]]{<<{}()>(<>())>[[{}[]]]}}}}][{([{[([]{})<()[]>][[<>{}]{()[]}]}(([()
+{[<<(<<<{[<<<<[]<>><()[]>>[({}[])[[]<>]]><((<><>)[{}<>])[{{}{}}[[]()]]>>{{{[<><>]<<>()>}[<[]{}>([][])]
+<(<{<(<({[[{((()[])[{}<>])([<>()]>}{[({}{})[(){}]]<[()<>]({}[])>}]{[<{[]{}}><{[]{}}[[][]]>][[<{}<>><()[]>]<[
+{<({[<((<<<{{([]<>}{<><>}}<{<>{}}[[]<>]>}>{<[{{}}(()())]>}>(<<{[(){}]<()[]>}({(){}}[()<>])>[<<<>[]>{[]
+{(({<{{{{{((<{[]<>>(<>{})>[[<>()]])<<(()())[<>]><[(){}][{}{}]>>)}({([[[]]]{<{}{}><()[]>})<{[(){}][[]()]}>
+<<[<<[((({[[(<{}[]>({}())){[()()]}][{{<>{}}<<>()>}[<{}[]>[<>[]]]]]{<(([]())([]()))>{([()()]<<>[]>)[<
+{([<<<({((<{{[<>[]][<>{}]}<<<>[]>[[][]]>}[{[()[]]<<>[]>}<[{}{}]<<><>>>]>({[<[]<>>]<<()()>([][])>}(((<
+(<{<((<{[[<[(<[]{}>{<>{}})][<([][])[{}<>]>[<{}<>>]]><<[(<>[])[{}<>]]{<{}{}><{}[]>}>(<([]<>){()[]}>)>]]}{({[<(
+[{{(({<<<<{{<({}()){{}{}}>[(()[])]}[([(){}]{<>[]})[(<>())[{}]]]}>[<<<{[]{}}{{}{}}>]{<[{}<>]>{(()())}}>[{(<[]<
+{[<<{<[[({{<<{()[]}<<><>>>([[]<>>[{}[]])>}[[[([]<>)[<>{}]]]<<[<>()](<>{})>>]})(((({({}[])<<><>>}([<>])))((<
+[{(({({<({(<{{[][]}({}<>)}[{()()}{[][]}]>(((<><>)(<>()))([{}()][{}()])))([{[[]()]<[]{}>}{(
+{<{{<[<<[(<([({}())[{}()]]{{{}<>}<[]>}){[((){})<[][]>]<([]())({}[])>}>{<(((){})[()<>])(<()[]>[(){}]
+{({({<{{(<([<[<><>]((){})>{{()[]}<<>{}>}]{[(<>())<{}[]>][{()<>}[[]()]>})>[[<{([])[()[]]}><<[(){}]({}())>>]{
+(<{{(<<<{(<(({<><>}{()[]})<[{}[]]([]())>)([(()<>)[[]<>]]({[]()}{{}{}}))))[(<{{()[]}<()[]>}((<><>))>[[
+<<[<([{<<[[({<[]<>><<>()>}{([]<>)[[]<>]}){[<{}{}><()[]>]<{<>()}{<>()}>}]{{<({}{})>})]>[<({<
+(<<[[({[({(<{{[]{}}<[]{}}}>[<<()<>><{}<>>>(<()()>{{}<>})])}{<({({}[])<()>}<([]())<{}<>>>)<<[(
+[<(<{(([(<([[<<>{}>(<>{})]](((()[])[[]()])[[{}<>]({}{})]))><<{<([]<>){[][]}>[{<>[]}<()<>>]}>(<((<>[]){()<>}
+[<{[[{(([[{[{<[]<>>(<>[])}<<<>()>{{}{}}>][({[][]}<<>>){(<>[])[<><>]}]}(([([][])(<>[])]{(()())}))](<<{
+((<{<<([<[(([{()()}((){})][<()[]><()[]>])<{({}<>){{}<>}}>)[{(<<><>>)<{{}[]}>}({(<>()){()}}{([
+[({{{{((([({{(<>[])[[]<>]}([{}])}(({<><>}{<>()})[[{}[]]]))<{[[<>{}](()[])](<()<>>{[]()})}{{<()()
+[<[<({[[({[[[<<>[]>]({[]}[<><>])]{[[()<>]([]())]<({}{})[[][]]>}]}<<(([()()]<()<>>)<{()()}[()[]]>
+{<([[<[<<(([<(()[])(()<>)>{[<><>](<>[])]]{({{}})}){<((<><>)<{}<>>)((()[])[[]()])>})<<(<(())(
+<[<((<{(<[[({{{}()}({}{})}}<[[()<>]]<[()()][<>]>>]<[([()()]({}<>))[<{}()>([]<>)]]>][{[[(()())[()]][[<>[]
+[{(<(<[((<{(({(){}}[()[]])<{[][]}(<>{})>)[(<<><>>[()[]]]{[{}[]]{()<>}}]}><[<[[{}()](()[])][(<>()){<>()}]>[{
+([({<({{{[[<[{{}<>}([][])]{[(){}]{()<>}}>][{[{[]<>}][<{}()>]}]]}{((<[{{}[]}(()()))[{<>[]}]>({(<>{})<[]<>>}
+{[({[<[([(<{((<>{})<{}{}>)}(<[[]()]<{}{}>>({{}[]}{[]<>}))><[((()[])(())){([]<>)[()[]]}]<({()
+[(<<<([{[[[<<<<>>{{}<>}>[{[]()}]>[([[]{}]{[]<>}){[<>()]}]]]]}]<<((<([{[][]}<{}<>>]<[[]{}][[]<>])){{[<>[]
+{[{{[[{{[<[<<{{}<>}<[]{}>><<()[]>[<>[]]>>[([<>{}](()()))]]>{({([{}[]](<><>))<<(){}>(<>{})>}({([]<>)[{}[])}(<<
+<{([[{<[<{{([(<>{})[<>()]]){{[()[]]([])}}}[{<((){})([]())>}(<{[][]}<<>{}>>[[[][]]<()()>])]}>[
+{(<[({{(<<<{[(()())]<[<>[]][{}{}]>}[[<()[]>{[][]}]]>(<((<>())[()[]]){{()[]}{[][]}}>({{[]<>}<[][]>}(<[]{}
+<{{[{((((<[{({[]{}}<(){}>)}[[{[][]}<<>{}>]<<[][]>{[]}>]]>{{([((){})<<>{}>]{{()()}})<[<<>()>](<<>>[()
+<([({(<<<{[<{(()<>)(<>[])}([<>]{<>{}})>]<(<<<><>><{}()>>[([][]){[]<>}])>}{[([[[]<>]{(){}}]<[{}<>]{{}<>}
+{<<<[{[(<[([([[]()]<()[]>)(([]())({}[]))]<[[()<>]]<[(){}]<[][]>>>)(<{<[][]>)<(()<>)<{}[]>>
+{[[<[[<(<[[{(<()<>>)<{{}<>}[[][]]>}<<(()()){[]{}}>{<[]()>>>]]>)({<<<<[{}{}]{<>()}>{<<><>>([]{})}>>[([<()()>(
+[[[{({{({[{[(({}())(<>[]))<<<>[]>[[]<>]>]<<<()()><<>>>[({}())(<>[])]>}[({<(){}>({}{})}[[{}()]]){[[[]<>
+<(((<<[{[[<({({}<>)[{}()]}[{[]{}}([]())]){([[]<>]<[]<>>)[(()[])[{}[]]]}>(<<<{}[]><()[]>)>[[<{}(
+[<<{[{{<<[[{<<()[]>(())><<{}()][<>()]>}({[{}{}][<>()]}<([]())([])>)]({{{[][]}[<>{}]}<[()]{{}()}>}(({
+{([(<[[<(<<<(<<><>><{}<>>)({{}()}[<>()])>{([(){}][[][]]){[<><>]{<><>}}}>>(({(<<><>><()<>>){{()<>}{(){}}}}
+[(<([[[([(({[[<>[]]]}))([{{[{}()]([]<>)}{{<>[]}[[][]]}}(<([]())>[([]{}){()<>}])][<{<()[]><()()>}>{<([
+{([[<<[[<[[[<[{}[]]{[]<>}>[<{}()>{<>[]}]]]<[<{[][]}(<>[])>[[{}[]]<[][]>]][((()[])[<>{}]){{{}()}[(){}]}]>]>
+{[[[<<{{[<<<([{}[]]<<>[]>)([()]<{}{}>)>({<<>{}>(()[])})>[(((<><>>{<>{}})<<<>[]>[[]()]>)({(()(
+[[[{<<(({{[((<{}<>>[{}])({<>{}}<{}{}>))[(<{}()>(<>{}))(<<><>>{{}{}})]]({{<()>}}(<{(){}](<><>)
+(({{[[[<[{<{[<{}()><<>{}>]}({[[]()]<{}[]>])>}[<{{(<><>)<{}()>}{{{}<>}{{}[]}}}(([<>[]]([][]))
+<[<<{({[(<(<{({}<>)<[][]>}{(()[])({}[])}>{(<{}{}>>})>([<<<<>{}>((){})>[(()())[[]()]]><{[{}<>]<<>
+[{<{[(<[[[{({({}<>)(()<>)}{<[][]>})}{[<[()[]]{[]<>]>{<{}()>(()())}]{[<()()>{<>[]}]<[<><>]>}}]
+({{<{[[[([({{<<>()>(()<>)}(<{}()><()[]>)}<[[{}()]<{}[]>]{((){}){{}[]}}>)[([{<><>}<()<>>][(<><>)(()())]
+(({<{{{[([{<<<{}{}>{[]{}}>([<>[]]{[]{}})>}{<<{[]{}}[[]{}]>{<<>{}>([]())}><(<(){}>({}[]))[(<>[])(()<>)]>
+<[<(<{[[<([({[<>()][<>{}]}{{()()}[<><>]})]<[[<[]()>]<[{}<>]([])>]{<[<>[]]<<>()>]((<>())[<>{}])}>)([{<[[][]]
+<<{{((({<<[[<{<>()}(()())>[(()[])[()<>]]]{({{}[]}[<><>])}]<{<<<><>>{{}[]}>}<[<[][]>[{}[]]](<()()>{[]{}})
+[<<{<{([{(({[{()[]}{()}][({}{})(()[])]}{({<>()})({[]()}({}[]))}))}][[[([[{<>[]}[{}[]]][[<><>]<()[]>]]([
+[([[{{<(<[{(<<()<>>><[[]()]{()()}>)<(({}()){[]<>})>}]>)>{<[<{{((()())({}<>)>{([]{}){{}<>}}}}<({
+((<<{(<[(<[[<({})>[{[][]}[<>[]]]]]>)]>)}([(<[[([(([][]))[{{}()}([][])]][((<><>){[]()})])]]<<(
+<<<<(<{[{[({<{(){}}[<>]>[<[]<>>{<>()}]}[<[<>()]>{[[]<>][{}[]}}])(<{<(){}>[{}{}]}<(()<>)<()[]>>>)][<{{<[]<
+(([[<{[({{{[<<<><>>(()())>({[]<>}(<>()))]{<[<>()][{}{}]>([[]()]((){}))}}((<({}{})[<>]>([<>()]{(){}})))}[<{([<
+{[([<<[([[<[(<[]()>{()[]})<{<>()}{(){}}>]><<{<[][]><{}()>}(<[]<>>([]<>])>>]{[[<<{}<>>({}[]
+{{[<<(<({[<<{<[]<>>}{(<>())}>[{[<>]{(){}}}]>]}{{{<([()<>]{<>{}})(<()[]>[[]()])><[<<>[]>({}{})]((()())[{
+[{{[<{<<{{<[<<()()>[{}]>([{}{}]({}{}))]{(<[][]>([][]))(([]{})<<>[]>)}>}({{<{<>[]}[<>()]>(({
+[<{[(<<[<<(([[<>[]]][([]())({}<>}])){(({[]()}{()<>})[<[]{}>(<><>)])[<[{}[]][{}{}]><{(){}}<{}{}>>]}>({<<[[]()
+[({[<<<({<({({{}<>}[[]{}])}({({}<>)<<>[]>}))([<{(){}}>])>}{<{[[{{}{}}(<>{})]]<[[()[]]<<><>>]{[<><>]<{}()>
+[<{<<<<(([([[{{}()}[<>]][((){})[[]{}]]](({[]()}[[]()])[{[]()}(<>[])])){[{<<><>>{{}<>}}<{()[]}[[]
+[{({<(((<({{({[]()}))[((()())<[][]>)<{<>{}}(<><>)>]}{[<[[][]](<><>)>][[{<>{}}[<>{}]](<<>[]>{[][]})]})>)))>}
+[[{[[{({[([(<<<>[]>[<><>]>([{}()][<>()]))<<[<>{}]{{}<>}>[<<>{}>([]{}]]>])<(<(<[]()>)[(()[])
+<([(<<[<<({{{([]{})}[{()<>}<[]()>]}}{(<{[]{}}([][])>)})[[[<[[][]]<<><>>><{{}{}}(<><>)>]<<(()())[(){}]>{
+[(<{[{({[({<{<{}[]><<>()>}{<{}()>[[][]]}><<{{}()}{(){}}>>}[<{{<>{}}{()())}>]){[<[{()()}<[]()>]><[[{
+<{<[{([([<<[<[<>()]{(){}}>][({{}[]}((){}))[<[][]><()<>>]]>>{{{<{<><>}{(){}}>({<><>}<()))}({<()><{}[]>}(<(
+({((([[{([<[(([]{})){[()<>][<><>]}]>{[<<{}{}><()[]>>(<<>>)]({<<><>>[<>{}]}{<[]{}><<>{}>})}])[(<(([<><>][{}{
+<[<(([(({([[<(()[])[[]{}]>{<<>{}>(<>{})}]]([([<>{}]{[]{}})][{<()>{()[]}}(({}[])(<>[]))]))})({{[(({(){}}[<>
diff --git a/source/day10/part1.d b/source/day10/part1.d
new file mode 100644
index 0000000..9a951b8
--- /dev/null
+++ b/source/day10/part1.d
@@ -0,0 +1,89 @@
+module day10.part1;
+
+import std.file;
+import std.stdio;
+import std.string;
+import std.algorithm;
+import std.container;
+import std.array;
+
+char getClosingChar(char c) {
+    if (c == '(') return ')';
+    if (c == '[') return ']';
+    if (c == '{') return '}';
+    if (c == '<') return '>';
+    return 0;
+}
+
+char isOpeningChar(char c) {
+    return c == '(' || c == '[' || c == '{' || c == '<';
+}
+
+char findFirstIllegalCharacter(string s) {
+    SList!char stack;
+    foreach (c; s) {
+        if (isOpeningChar(c)) {
+            stack.insertFront(c);
+        } else {
+            char opening = stack.front();
+            if (getClosingChar(opening) != c) {
+                return c;
+            } else {
+                stack.removeFront();
+            }
+        }
+    }
+    return 0;
+}
+
+bool isCorrupted(string s) {
+    return s.findFirstIllegalCharacter != 0;
+}
+
+string completeString(string s) {
+    SList!char stack;
+    foreach (c; s) {
+        if (isOpeningChar(c)) {
+            stack.insertFront(c);
+        } else {
+            char opening = stack.front();
+            if (getClosingChar(opening) != c) {
+                throw new Exception("Corrupt string!");
+            } else {
+                stack.removeFront();
+            }
+        }
+    }
+    auto a = appender!string;
+    while (!stack.empty()) {
+        a ~= stack.front.getClosingChar;
+        stack.removeFront();
+    }
+    return a[];
+}
+
+ulong getSuffixScore(string s) {
+    ulong score = 0;
+    foreach (c; s) {
+        score *= 5;
+        if (c == ')') score += 1;
+        if (c == ']') score += 2;
+        if (c == '}') score += 3;
+        if (c == '>') score += 4;
+    }
+    return score;
+}
+
+void syntaxChecker() {
+    int[char] scores;
+    scores[')'] = 3;
+    scores[']'] = 57;
+    scores['}'] = 1197;
+    scores['>'] = 25_137;
+    readText("source/day10/input.txt").strip.split("\n")
+        .map!(strip)
+        .filter!(s => !s.isCorrupted)
+        .map!(completeString)
+        .map!(getSuffixScore)
+        .array.sort[$/2 .. $/2 + 1].writeln;
+}
\ No newline at end of file
diff --git a/source/day10/test_input.txt b/source/day10/test_input.txt
new file mode 100644
index 0000000..b1518d9
--- /dev/null
+++ b/source/day10/test_input.txt
@@ -0,0 +1,10 @@
+[({(<(())[]>[[{[]{<()<>>
+[(()[<>])]({[<{<<[]>>(
+{([(<{}[<>[]}>{[]{[(<()>
+(((({<>}<{<{<>}{[]{[]{}
+[[<[([]))<([[{}[[()]]]
+[{[{({}]{}}([{[{{{}}([]
+{<[[]]>}<{[{[{[]{()[[[]
+[<(<(<(<{}))><([]([]()
+<{([([[(<>()){}]>(<<{{
+<{([{{}}[<[[[<>{}]]]>[]]