Compilare: main.cpp: In function 'int main()': main.cpp:33:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int it = 0; it < graph[current].size(); ++it) { ~~~^~~~~~~~~~~~~~~~~~~~~~~ main.cpp:14:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.in", "r", stdin); ^ main.cpp:15:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.out", "w", stdout); ^ main.cpp:17:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ main.cpp:20:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &s, &d); ^