#include<bits/stdc++.h>
using namespace std;
#define int long long
int n, m;
int sum[100007];
int ans = 1e9;
signed main()
{
	cin >> n >> m;
	sum[0] = m;
	for (int i = 1; i <= n; i++)
	{
		int x;
		cin >> x;
		sum[i] = sum[i - 1] + x;
		if(n % i == 0)
			ans = min(ans, sum[i] * (n / i) + (n / i - 1) * m);
		else
			ans = min(ans, sum[i] * (n / i) + sum[n % i] + (n / i) * m);
	}
	cout << ans;
	return 0;
}