/in/foo.cc: In function 'void revice(int, int)':
/in/foo.cc:11:7: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(t >= s.length())
     ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:27:6: warning: unused variable 't' [-Wunused-variable]
  int t = 0;
      ^