rt.

#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e5 + 1;
int m, n, sum, cnt, md, ans, a[N];
signed main()
{
	cin >> m >> n;
	for(int i = 1; i <= n; i++)
	{
		cin >> a[i]; 
		sum += a[i];
	}
	sum -= m, cnt = sum / n, md = sum % n;
	for(int i = 1; i <= n; i++)
	{
		if(i <= md)
		{
			ans += (cnt + 1) * (cnt + 1);
		}
		else
		{
			ans += cnt * cnt;
		}
	}
	cout << ans;
	return 0;
}