/in/foo.cc: In function 'int main()':
/in/foo.cc:20:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0;i< str.size();i++)
                ~^~~~~~~~~~~~
/in/foo.cc:31:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(j = 0;j < ss.size();j++)
              ~~^~~~~~~~~~~
/in/foo.cc:36:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(j == ss.size())
       ~~^~~~~~~~~~~~
/in/foo.cc:49:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(j = 0;j < ss.size();j++)
              ~~^~~~~~~~~~~
/in/foo.cc:54:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(j == ss.size())
       ~~^~~~~~~~~~~~
/in/foo.cc:16:6: warning: unused variable 'flag' [-Wunused-variable]
  int flag = 0;
      ^~~~