#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <vector>

#define rep(x,to) for(int (x)=0;(x)<(to);(x)++)

using namespace std;
typedef vector<int> VI;


int main()
{

	int T, N;
	cin >> T >> N;
	VI c(N), v(N);
	rep(i, N) cin >> c[i];
	rep(i, N) cin >> v[i];

	VI cp(T + 5,0); //, np=cp;
	rep(i, N) for(int vl=v[i]; vl>0; vl>>=1){
		for(int j=T+1;j>= 0;--j) {
			if(j + c[i]<T+2){
				cp[j + c[i]] = max(cp[j + c[i]], cp[j] + vl);
			}
		}
		//printf("%2d:",i);rep(i, T+2) printf("%2d ", cp[i]);puts("");
	}
		
	cout << cp[T] << endl;
	return 0;
}
/*
20
5
10 7 9 5 7
5 8 2 8 1
-->20 */