/in/foo.cc: In function 'int main()':
/in/foo.cc:11:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < s.size(); i++)
                    ~~^~~~~~~~~~
/in/foo.cc:17:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < zero_index.size(); i++)
                        ~~^~~~~~~~~~~~~~~~~~~
/in/foo.cc:22:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
          for(int i = 0; i < one_index.size(); ++i)
                         ~~^~~~~~~~~~~~~~~~~~
/in/foo.cc:28:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
          for(int i = 0; i < zero_index.size(); ++i)
                         ~~^~~~~~~~~~~~~~~~~~~
/in/foo.cc:30:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
          for(int i = 0; i < one_index.size(); ++i)
                         ~~^~~~~~~~~~~~~~~~~~