/*░░░░░░░▄▄▄▀▀▀▄▄███▄
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░▐█▀▄▀▄▄▄▄▀▀▀▀▌░░░░░▐█▄
░▌▄▄▀▀░░░░░░░░▌░░░░▄███████▄
░░░░░░░░░░░░░▐░░░░▐███████████▄
░░░░░le░░░░░░░▐░░░░▐█████████████▄
░░░░toucan░░░░░░▀▄░░░▐██████████████▄
░░░░░░has░░░░░░░░▀▄▄████████████████▄
░░░░░arrived░░░░░░░░░░░░█▀██████*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int MAXN = 1007, MAXP = 103;
const ll INF = (ll)1e18;
ll dp[2][MAXN * MAXP];
int p[MAXN];
int ps[MAXN];
int main()
{
#ifdef LOCAL
	freopen("input.txt", "r", stdin);
#endif
	int n, m;
	scanf("%d %d", &n, &m);
	int sum = 0;
	for (int i = 1; i <= m; i++)
	{
		scanf("%d", &p[i]);
		sum += p[i];
	}
	sort(p + 1, p + 1 + m);
	reverse(p + 1, p + 1 + m);
	for (int i = 1; i <= m; i++)
	{
		ps[i] = ps[i - 1] + p[i];
	}
	for (int i = 0; i < 2; i++)
	{
		for (int j = 0; j <= sum; j++)
		{
			dp[i][j] = -INF;
		}
	}
	int cur = 0, nxt = 1;
	dp[cur][0] = 0;
	for (int i = 1; i <= m; i++)
	{
		for (int j = 0; j <= sum; j++)
		{
			dp[nxt][j] = -INF;
		}
		for (int j = 0; j <= sum; j++)
		{
			int sumLeft = j, sumRight = ps[i - 1] - sumLeft;
			int sumMore = sum - sumLeft - sumRight;
			int dist = n - i + 1;
			dp[nxt][j + p[i]] = max(dp[nxt][j + p[i]], dp[cur][j] + 1LL * sumMore * (sumLeft) + 1LL * p[i] * sumRight * dist);
			dp[nxt][j] = max(dp[nxt][j], dp[cur][j] + 1LL * sumMore * (sumRight)  + 1LL * p[i] * sumLeft * dist);
		}
		/*for (int j = 0; j <= sum; j++)
		{
			cerr << i << " " << j << " " << dp[nxt][j] << endl;
		}*/
		swap(cur, nxt);
	}
	ll res = 0;
	for (int i = 0; i <= sum; i++)
	{
		res = max(res, dp[cur][i]);
	}
	printf("%lld\n", res);
}