/in/foo.cc: In function 'int main()':
/in/foo.cc:8:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<strlen(s);++i){
                ^
/in/foo.cc:5:6: warning: unused variable 'cnt' [-Wunused-variable]
  int cnt=0;
      ^