Compilare: main.cpp: In member function 'void Graph::bfs_min_distance(int)': main.cpp:39:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < adj[index].size() ; ++i) { ~~^~~~~~~~~~~~~~~~~~~ main.cpp:50:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1 ; i < distance.size() ; ++i) { ~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:62:31: 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:63:33: 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:65:29: 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:71:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &src, &dest); ^