/in/foo.cc: In function 'int main()':
/in/foo.cc:14:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i=0;i<str.length();i++){
                 ^
/in/foo.cc:22:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(i==str.length()-1){
         ^