/in/foo.cc: In function 'bool SPFA(long long int, long long int)':
/in/foo.cc:75:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int z = 0; z < edge[x].size(); z++) {
                         ~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'newpair ZKW_DFS(long long int, long long int, long long int)':
/in/foo.cc:129:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int& z = head[x]; z < edge[x].size(); z++) {
                            ~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'void costflow()':
/in/foo.cc:155:40: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
         while (ans = ZKW_DFS(0, st, inf)) {
                                        ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:180:19: warning: unused variable 'flow' [-Wunused-variable]
         int x, y, flow, weight;
                   ^~~~