Compilare: user.cpp: In function ‘int BFS()’: user.cpp:15:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<G[C[i]].size();j++) ^ user.cpp:26:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:30:32: 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); ^ user.cpp:31:34: 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); ^ user.cpp:32:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&N,&M,&s); ^ user.cpp:37:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^