Compilare: user.c: In function ‘main’: user.c:8:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sir.in","r",stdin),freopen("sir.out","w",stdout),scanf("%d%d%d%d",&n,&x,&y,&z); ^ user.c:8:40: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sir.in","r",stdin),freopen("sir.out","w",stdout),scanf("%d%d%d%d",&n,&x,&y,&z); ^ user.c:8:68: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("sir.in","r",stdin),freopen("sir.out","w",stdout),scanf("%d%d%d%d",&n,&x,&y,&z); ^ user.c:10:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",a+i); ^