/in/foo.cc: In function 'int main()':
/in/foo.cc:10:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < s.length(); i++){
                 ~~^~~~~~~~~~~~
/in/foo.cc:15:20: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
  s = s.erase(pos, 1);
                    ^