foo.cc: In function ‘bool SPFA(int, int)’:
foo.cc:91:27: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<edgenode>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   91 |         for (int z = 0; z < edge[x].size(); z++) {
      |                         ~~^~~~~~~~~~~~~~~~
foo.cc: In function ‘newpair ZKW_DFS(int, int, int)’:
foo.cc:146:30: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<edgenode>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
  146 |     for (int& z = head[x]; z < edge[x].size(); z++) {
      |                            ~~^~~~~~~~~~~~~~~~
foo.cc: In function ‘void costflow()’:
foo.cc:174:20: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  174 |         while (ans = ZKW_DFS(0, st, inf)) {
      |                ~~~~^~~~~~~~~~~~~~~~~~~~~