/in/foo.cc: In member function 'int BitSet::test(int)':
/in/foo.cc:41:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (pos > (S.size() - 1))return 0;
             ~~~~^~~~~~~~~~~~~~~~
/in/foo.cc: In member function 'void BitSet::flip(int)':
/in/foo.cc:74:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (pos > (S.size() - 1))
             ~~~~^~~~~~~~~~~~~~~~