#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<long double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<29;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-18;
const ll mod=1e9+7;
const int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};

int n,m;
vi a,b,v,w;

int main(){
	cin>>n>>m;
	a=b=vi(m);
	for(int i=0;i<m;i++) cin>>a[i];
	for(int i=0;i<m;i++) cin>>b[i];
	for(int i=0;i<m;i++){
		while(b[i]){
			v.push_back(b[i]);
			w.push_back(a[i]);
			b[i]/=2;
		}
	}
	vi dp(n+1);
	for(int i=0;i<v.size();i++) for(int j=n;j>=w[i];j--) dp[j]=max(dp[j],dp[j-w[i]]+v[i]);
	int res=0;
	for(auto i:dp) res=max(res,i);
	cout<<res<<endl;
}