#include <bits/stdc++.h>
using namespace std;

int main(void) {
	int T, N;
	cin >> T >> N;
	vector<int> C(N), V(N);
	for(int i = 0; i < N; ++i) cin >> C[i];
	for(int i = 0; i < N; ++i) cin >> V[i];
	
	vector<int> dp(T + 1, -1e9);
	dp[0] = 0;
	for(int i = 0; i < N; ++i) {
		vector<int> ndp = dp;
		int nV = 0;
		for(int k = 1; k < 100; ++k) {
			if(V[i] == 0) break;
			nV += V[i];
			V[i] /= 2;
			
			for(int j = 0; j <= T; ++j) if(dp[j] >= 0 and j + k * C[i] <= T) ndp[j + k * C[i]] = max(ndp[j + k * C[i]], dp[j] + nV);
		}
		swap(ndp, dp);
	}
	
	int ans = 0;
	for(int i = 0; i <= T; ++i) ans = max(ans, dp[i]);
	cout << ans << endl;
	return 0;
}