/in/foo.cc: In function 'void bfs(int, std::vector<int>&)':
/in/foo.cc:14:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < tmp.size(); ++i) {
                     ~~^~~~~~~~~~~~
/in/foo.cc:21:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         res = res <= (inf_num + tmp.size() - 1) ? res : (inf_num + tmp.size() - 1);
               ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:24:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < tmp.size(); ++i) {
                     ~~^~~~~~~~~~~~