/in/foo.cc: In function 'int main()':
/in/foo.cc:15:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(index!=s.size()){
              ^
/in/foo.cc:17:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(k!=string::npos) {
        ^