Compilare: main.cpp: In function 'int main()': main.cpp:35:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0; k<arcs[a].size(); ++k) ~^~~~~~~~~~~~~~~ main.cpp:47:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0; k<arcs[a].size(); ++k) ~^~~~~~~~~~~~~~~ main.cpp:8:39: 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:9:41: 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); ^ main.cpp:12:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:22:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &a, &b, &c); ^