/in/foo.cc: In function 'bool cmp(std::vector<std::__cxx11::basic_string<char> >&, std::vector<std::__cxx11::basic_string<char> >&)':
/in/foo.cc:18:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i != s1.size(); i++)
                     ~~^~~~~~~~~~~~
/in/foo.cc: In function 'void dfs(std::__cxx11::string, int, int)':
/in/foo.cc:25:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (now == ans.size()) {
         ~~~~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:46:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i != b.size(); i++) {
                     ~~^~~~~~~~~~~
/in/foo.cc:48:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (i != b.size() - 1)cout << ',';
             ~~^~~~~~~~~~~~~~~