Compilare: user.cpp: In function ‘int main()’: user.cpp:48:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<comp.size();i++) ^ user.cpp:50:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<comp[i].size();j++) printf("%d ",comp[i][j]); ^ user.cpp:29:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in", "r", stdin); ^ user.cpp:30:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out", "w", stdout); ^ user.cpp:32:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:35:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^