/in/foo.cc: In function 'void search(int)':
/in/foo.cc:28:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < V[current].size(); i++)
                   ~~^~~~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:60:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < E.size(); i++) R = std::min(R, D[E[i]]);
                  ~~^~~~~~~~~~