Compilare: main.cpp: In function 'int main()': main.cpp:64:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<G[edge.y].size();++j) ~^~~~~~~~~~~~~~~~~ main.cpp:26:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.in", "r", stdin); ^ main.cpp:27:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bellmanford.out", "w", stdout); ^