#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <numeric>
#include <cstring>
#include <cmath>
#include <set>
#include <queue>
#include <stack>

const int MOD = 1e9 + 7;
const int iINF = 1000000000;
const long long int llINF = 1000000000000000000;
#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;
using ll = long long int;
using P = pair<int, int>;
using edge = struct
{
    int to;
    int cost;
};

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int T, N;
int dp[20][10000];

int main()
{
    cin >> T >> N;
    vector<int> c(N), v(N);
    rep(i, N) cin >> c[i];
    rep(i, N) cin >> v[i];
    memset(dp, -1, sizeof(dp));
    dp[0][0] = 0;

    for (int i = 0; i < N; i++)
    {
        rep(j, T + 1)
        {
            dp[i + 1][j] = dp[i][j];
            int sum = 0;
            for(int k = v[i], cnt = 1; k > 0; k /= 2, cnt++)
            {
                sum += k;
                if(j - c[i] * cnt >= 0 && dp[i][j - c[i] * cnt] != -1)
                {
                    dp[i + 1][j] = max(dp[i + 1][j], dp[i][j - c[i] * cnt] + sum);
                }
            }
        }
    }
    int ans = 0;
    rep(i, T + 1) ans = max(ans, dp[N][i]);

    cout << ans << endl;
    return 0;
}