Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:21:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < neighbours.size(); i++){ ^ user.cpp: In function ‘int main()’: user.cpp:34:29: 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:35:31: 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:36:26: 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:39:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b); ^