#include<bits/stdc++.h>
#define endl '\n'
using namespace std;

const int N = 1e4 + 9;

int n, m, a[N], b[N], dp[N * 2];

int main() {
	ios::sync_with_stdio(false); cin.tie(0);
	cin >> n >> m;
	for (int i = 1; i <= m; i++) cin >> a[i];
	for (int i = 1; i <= n; i++) cin >> b[i];
	dp[1] = 0;
	for (int i = 2; i <= n + n; i++) {
		dp[i] = -1e9;
		for (int j = 1; j <= m; j++) {
			if (i - a[j] < 1 || i - a[j] > n) continue;
			dp[i] = max(dp[i - a[j]] + b[i - a[j]], dp[i]);
		}
	}
	int ans = -1e9;
	for (int i = n; i <= n + n; i++) ans = max(ans, dp[i]);
	cout << ans << endl;
	return 0;
}