/in/foo.cc: In function 'int main()':
/in/foo.cc:22:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (e == string::npos)
       ~~^~~~~~~~~
/in/foo.cc:29:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (e == s.length() - 1) {
       ~~^~~~~~~~~~~~~~~~~
/in/foo.cc:80:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while (b < s.length()) {
         ~~^~~~~~~~~~~~