Compilare: main.cpp: In member function 'long long int MinCostMaxFlow::solve()': main.cpp:104:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < e.size(); i++) if (e[i].f > 0) ret += e[i].f * e[i].cost; ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:114:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fmcm.in", "r", stdin); ^ main.cpp:115:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fmcm.out", "w", stdout); ^