#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
	int t, n;
	cin >> t >> n;
	vector<int> c(1 + n);
	for (int i = 1; i <= n; ++i) {
		cin >> c[i];
	}
	vector<int> v(1 + n);
	for (int i = 1; i <= n; ++i) {
		cin >> v[i];
	}
	// [until ?-th atraction][time]
	vector<vector<int> > satisfaction(n + 1, vector<int>(t + 1));
	fill(satisfaction[0].begin(), satisfaction[0].end(), 0);
	for (int i = 1; i <= n; ++i) {
		for (int k = 0; k <= t; ++k) {
			int maxSatisfaction = 0;
			int ithAttractionSatisfaction = 0;
			int ithAttractionSatisfactionDelta = v[i];
			for (int ithAttractionCount = 0;
				ithAttractionSatisfactionDelta > 0;
				++ithAttractionCount) {
				ithAttractionSatisfaction += ithAttractionSatisfactionDelta;
				if (k - c[i] * ithAttractionCount >= 0) {
					maxSatisfaction = max(maxSatisfaction,
						satisfaction[i - 1][k - c[i] * ithAttractionCount]
						+ ithAttractionSatisfaction);
				}
				ithAttractionSatisfactionDelta /= 2;
			}
			satisfaction[i][k] = maxSatisfaction;
		}
	}
	cout << satisfaction[n][t] << endl;
	return 0;
}