/in/foo.cc: In function 'int main()':
/in/foo.cc:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (i = 1; i < s.length(); i++) {
              ~~^~~~~~~~~~~~
/in/foo.cc:10:9: warning: unused variable 'q' [-Wunused-variable]
  int i, q, h,n;
         ^
/in/foo.cc:10:12: warning: unused variable 'h' [-Wunused-variable]
  int i, q, h,n;
            ^