Compilare: user.cpp: In function ‘int main()’: user.cpp:33:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int z=0;z<nodes[current].size();z++){ ^ user.cpp:16:30: 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:17:32: 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:18:27: 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:24:67: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (int j=0;j<M;++j) scanf("%d%d",&x,&y), nodes[x].push_back(y); ^