using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;
using System.IO;

class Program
{
    static void Main()
    {
        new Magatro().Solve();
    }
}

class Magatro
{
    private int T, N;
    private int[] C, V;
    private void Scan()
    {
        T = int.Parse(Console.ReadLine());
        N = int.Parse(Console.ReadLine());
        C = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        V = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
    }

    private int[] F(int n)
    {
        List<int> result = new List<int>();
        result.Add(0);
        while (n > 0)
        {
            result.Add(result.Last() + n);
            n /= 2;
        }
        return result.ToArray();
    }

    public void Solve()
    {
        Scan();
        var dp = (new int[T + 1]).Select(i => -1).ToArray();
        dp[0] = 0;
        for (int i = 0; i < N; i++)
        {
            var l = F(V[i]);
            for (int j = T; j >= 0; j--)
            {
                if (dp[j] == -1) continue;
                for (int k = 0; k < l.Length; k++)
                {
                    int next = j + C[i] * k;
                    if (next > T) continue;
                    dp[next] = Math.Max(dp[next], dp[j] + l[k]);
                }
            }
        }
        Console.WriteLine(dp.Max());
    }
}