Compilare: user.cpp: In function ‘int main()’: user.cpp:25:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v[i].size()<y2) p=v[i].size(); ^ user.cpp:33:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(v[i].size()>=c) printf("%d\n",v[i][c-1]); ^ user.cpp:10:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("camion.in","r",stdin); ^ user.cpp:11:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("camion.out","w",stdout); ^ user.cpp:13:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&m,&k,&c); ^ user.cpp:21:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&x1,&y1,&x2,&y2); ^