Compilare: user.cpp: In function ‘int main()’: user.cpp:25:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<nivel[i].size();j++) printf("%d ",nivel[i][j]); printf("\n"); ^ user.cpp:15:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nivele2.in","r",stdin); ^ user.cpp:16:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nivele2.out","w",stdout); ^ user.cpp:17:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:19:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^