/in/foo.cc: In function 'bool check()':
/in/foo.cc:8:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<=m.size()/2;i++)
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:39:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i=1;i<=30;i++)
  ^~~
/in/foo.cc:41:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
   if(check()){
   ^~
/in/foo.cc:42:21: error: 'i' was not declared in this scope
    printf("STEP=%d",i);
                     ^