Compilare: user.cpp: In function ‘int main()’: user.cpp:23:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0; j<v[y].size(); i++) ^ user.cpp:30:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<v[y].size(); j++) ^ user.cpp:10:36: 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:11:38: 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:12:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^ user.cpp:15:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&op,&x); ^