Compilare: user.c: In function ‘nth_element’: user.c:54:44: warning: operation on ‘arr[j]’ may be undefined [-Wsequence-point] arr[i]=arr[i]^arr[j]^(arr[j]=arr[i]);i++; j--; ^ user.c: In function ‘read’: user.c:18:13: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(FIN, "r", stdin); ^ user.c:20:11: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &k); ^ user.c:22:35: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] for(i = 1; i <= n; i++) scanf("%d", &arr[ i ]); ^ user.c: In function ‘main’: user.c:70:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(FOUT, "w", stdout); ^