/in/foo.cc: In function 'int main()':
/in/foo.cc:70:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i=0;i<n.length();i++)
               ~^~~~~~~~~~~
/in/foo.cc:81:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for (;k>=1;k--)
  ^~~
/in/foo.cc:82:21: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   printf("%d",c[k]);printf("\n"); 
                     ^~~~~~
/in/foo.cc:57:7: warning: unused variable 's' [-Wunused-variable]
  char s[]="square.in";
       ^
/in/foo.cc:58:7: warning: unused variable 't' [-Wunused-variable]
  char t[]="square.out";
       ^