/in/foo.cc: In function 'int mian()':
/in/foo.cc:27:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
     if(s[0]=='+')++hd;while(s[hd]==48)++hd;
     ^~
/in/foo.cc:27:23: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
     if(s[0]=='+')++hd;while(s[hd]==48)++hd;
                       ^~~~~
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status