Compilare: user.cpp: In function ‘void bf()’: user.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<A[Q.front()].size(); i++) ^ user.cpp: In function ‘void postbf()’: user.cpp:42:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<A[P.front()].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:95:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<R.size(); i++) ^ user.cpp:64:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.in", "r", stdin); ^ user.cpp:65:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.out", "w", stdout); ^ user.cpp:67:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &n, &m, &x, &y); ^ user.cpp:70:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^