Compilare: main.cpp: In function 'int main()': main.cpp:74:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1 ; i < distance.size() ; ++i) { ~~^~~~~~~~~~~~~~~~~ main.cpp:59:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.in", "r", stdin); ^ main.cpp:60:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.out", "w", stdout); ^ main.cpp:62:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &N, &M, &S); ^ main.cpp:68:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &src, &dest); ^