foo.cc: In function 'void DFS(std::string, long long int)':
foo.cc:50:54: warning: comparison of integer expressions of different signedness: 'long long int' and 'const size_type' {aka 'const long unsigned int'} [-Wsign-compare]
   50 |                 while ((pos = now.find(it->fi, pos)) != string::npos)
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
foo.cc:54:43: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |                         for (int i = 0; i < v[it->se].size(); ++i)
      |                                         ~~^~~~~~~~~~~~~~~~~~

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