/in/foo.cc: In function 'int main()':
/in/foo.cc:22:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int j=0;j<s.length();j++) {
              ^
/in/foo.cc:43:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int j=0;j<s.length();j++){
              ^