Compilare: user.cpp: In function ‘int check(int)’: user.cpp:13:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<v[r].size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:33:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hashuri.in","r",stdin); ^ user.cpp:34:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hashuri.out","w",stdout); ^ user.cpp:35:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:38:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&op,&x); ^