#include <bits/stdc++.h>   using namespace std;   int main() {     unsigned long long n, i, j, sum, k, temp;     scanf( %llu , &n);     unsigned long long a[n];     for (i = 0; i < n; i++) {       scanf( %llu , &a[i]);     }     sum = 0;     sort(a, a + n);     k = n / 2;     for (i = 0; i < k; i++) {       temp = (a[i] + a[n - 1 - i]);       sum += (temp * temp);     }     printf( %llu n , sum);     return 0;   }   