#include <bits/stdc++.h>  

using namespace std;

//#define int long long
#define FOR(i, j, k) for(int i = j; i < (int)k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define INF (1 << 30)

typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<P, int> Pi;

const int MOD = 1e9 + 7;
const int dy[] = {0, 0, 1, -1};
const int dx[] = {1, -1, 0, 0};

template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

int dp[1000][10001];
vector<int> c, v;

signed main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int t, n;
    cin >> t >> n;
    int tmp[100];
    rep(i, n) cin >> tmp[i];
    rep(i, n) {
        int a;
        cin >> a;
        while(a > 0) {
            v.push_back(a);
            c.push_back(tmp[i]);
            a /= 2;
        }
    }
    rep(i, c.size()) rep(j, t + 1) {
        if(j < c[i]) {
            dp[i + 1][j] = dp[i][j];
        }
        else {
            dp[i + 1][j] = max(dp[i][j], dp[i][j - c[i]] + v[i]);
        }
    }
    cout << dp[c.size()][t] << endl;
    return 0;
}