Compilare: user.c: In function ‘main’: user.c:4:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sistem.in","r",stdin),freopen("sistem.out","w",stdout),scanf("%d",&n),a[0][1]=a[3][1]=a[0][0]=a[1][0]=a[2][0]=a[3][0]=1; ^ user.c:4:43: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sistem.in","r",stdin),freopen("sistem.out","w",stdout),scanf("%d",&n),a[0][1]=a[3][1]=a[0][0]=a[1][0]=a[2][0]=a[3][0]=1; ^ user.c:4:74: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("sistem.in","r",stdin),freopen("sistem.out","w",stdout),scanf("%d",&n),a[0][1]=a[3][1]=a[0][0]=a[1][0]=a[2][0]=a[3][0]=1; ^