Error(s):

std.conv.ConvException@/usr/include/dmd/phobos/std/conv.d(1735): Unexpected '' when converting from type char[] to type int
----------------
/var/www/service/usercode/716146850/a.out(pure @safe int std.conv.to!(int).to!(char[]).to(char[])+0x20) [0x442d08]
/var/www/service/usercode/716146850/a.out(pure @safe int source.main().__lambda1!(char[]).__lambda1(char[]).__lambda2!(char[]).__lambda2(char[])+0x20) [0x442ce0]
/var/www/service/usercode/716146850/a.out(pure @property @safe int std.algorithm.iteration.__T9MapResultS586source4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult.front()+0x3c) [0x443824]
/var/www/service/usercode/716146850/a.out(@safe void std.format.formatRange!(std.stdio.File.LockingTextWriter, std.algorithm.iteration.__T9MapResultS586source4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult, char).formatRange(ref std.stdio.File.LockingTextWriter, ref std.algorithm.iteration.__T9MapResultS586source4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult, ref std.format.FormatSpec!(char).FormatSpec)+0x151) [0x4452c9]
/var/www/service/usercode/716146850/a.out(@safe void std.format.formatValue!(std.stdio.File.LockingTextWriter, std.algorithm.iteration.__T9MapResultS586source4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult, char).formatValue(std.stdio.File.LockingTextWriter, ref std.algorithm.iteration.__T9MapResultS586source4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult, ref std.format.FormatSpec!(char).FormatSpec)+0x2f) [0x44513f]
/var/www/service/usercode/716146850/a.out(@safe void std.format.formatElement!(std.stdio.File.LockingTextWriter, std.algorithm.iteration.__T9MapResultS586source4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult, char).formatElement(std.stdio.File.LockingTextWriter, std.algorithm.iteration.__T9MapResultS586source4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult, ref std.format.FormatSpec!(char).FormatSpec)+0x46) [0x4450e6]
/var/www/service/usercode/716146850/a.out(void std.format.formatRange!(std.stdio.File.LockingTextWriter, std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take, char).formatRange(ref std.stdio.File.LockingTextWriter, ref std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take, ref std.format.FormatSpec!(char).FormatSpec)+0xc8) [0x444928]
/var/www/service/usercode/716146850/a.out(void std.format.formatValue!(std.stdio.File.LockingTextWriter, std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take, char).formatValue(std.stdio.File.LockingTextWriter, ref std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take, ref std.format.FormatSpec!(char).FormatSpec)+0x2f) [0x444827]
/var/www/service/usercode/716146850/a.out(void std.format.formatGeneric!(std.stdio.File.LockingTextWriter, std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take, char).formatGeneric(std.stdio.File.LockingTextWriter, const(void)*, ref std.format.FormatSpec!(char).FormatSpec)+0x4a) [0x4447ca]
/var/www/service/usercode/716146850/a.out(uint std.format.formattedWrite!(std.stdio.File.LockingTextWriter, char, std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take).formattedWrite(std.stdio.File.LockingTextWriter, const(char[]), std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take)+0x56a) [0x4446a2]
/var/www/service/usercode/716146850/a.out(void std.stdio.File.write!(std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take, char).write(std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take, char)+0xa9) [0x4440c9]
/var/www/service/usercode/716146850/a.out(void std.stdio.writeln!(std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take).writeln(std.range.Take!(std.algorithm.iteration.__T9MapResultS246source4mainFZ9__lambda1TS3std5stdio4File15__T6ByLineTaTaZ6ByLineZ.MapResult).Take)+0x52) [0x443fe2]
/var/www/service/usercode/716146850/a.out(_Dmain+0x78) [0x43e690]
/var/www/service/usercode/716146850/a.out(_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv+0x1f) [0x44af6b]
/var/www/service/usercode/716146850/a.out(void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate())+0x2a) [0x44aebe]
/var/www/service/usercode/716146850/a.out(void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).runAll()+0x30) [0x44af24]
/var/www/service/usercode/716146850/a.out(void rt.dmain2._d_run_main(int, char**, extern (C) int function(char[][])*).tryExec(scope void delegate())+0x2a) [0x44aebe]
/var/www/service/usercode/716146850/a.out(_d_run_main+0x1dc) [0x44ae38]
/var/www/service/usercode/716146850/a.out(main+0x17) [0x447217]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5) [0x7f6fd5e08ec5]