using System;
using System.Globalization;
using System.Linq;

class Program
{
    public static void Main(string[] args)
    {
        var t = int.Parse(Console.ReadLine());
        var n = int.Parse(Console.ReadLine());
        var ci = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        var vi = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

        int[] dp = new int[t + 1];
        int[,] counts = new int[t+ 1, n];
        for (int dt = 1; dt <= t; dt++)
        {
            int next = -1;
            int maxIndex = -1;
            for (int k = 0; k < n; k++)
            {
                var current = 0;
                if (dt - ci[k] >= 0)
                {
                    current = dp[dt - ci[k]] + (int) (vi[k]*Math.Pow(1/2d, counts[dt - ci[k], k]));
                }
                else
                {
                    continue;
                }
                if(next < current)
                {
                    next = current;
                    maxIndex = k;
                }
            }
            if (next == - 1)
            {
                dp[dt] = dp[dt-1];
                for (int i = 0; i < n; i++)
                {
                    if (dt - ci[i] >= 0)
                    {
                        counts[dt, i] = counts[dt - ci[i], i];
                    }
                    else
                    {
                        counts[dt, i] = 0;
                    }
                }
                continue;
            }
            dp[dt] = next;
            for (int i = 0; i < n; i++)
            {
                if (dt - ci[i] >= 0)
                {
                    counts[dt, i] = counts[dt - ci[i], i];
                }
                else
                {
                    counts[dt, i] = 0;
                }
            }
            counts[dt, maxIndex]++;
        }
        Console.WriteLine(dp[t].ToString(CultureInfo.InvariantCulture));
    }
}