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

class Template
{
	static Scanner sc;
	public static void Main(string[] args)
	{
		sc = new Scanner();
		int T = sc.nextInt();
		int N = sc.nextInt();
		var c = sc.nextIntArray();
		var v = sc.nextIntArray();
		int[][] dp = new int[N + 1][];
		for (int i = 0; i <= N; i++)
		{
			dp[i] = Array.ConvertAll(new int[T * 2], e => e = -1);
		}
		dp[0][0] = 0;
		for (int i = 0; i < N; i++)
		{
			for (int j = 0; j < T + 1; j++)
			{
				int vbuf = v[i];
				int time = c[i];
				int vsum = 0;
				dp[i + 1][j] = Math.Max(dp[i][j], dp[i + 1][j]);
				while (vbuf > 0)
				{
					vsum += vbuf;
					if (j - time >= 0 && dp[i][j - time] != -1)
					{
						dp[i + 1][j] = Math.Max(dp[i + 1][j], dp[i][j - time] + vsum);
					}
					vbuf /= 2;
					time += c[i];
				}
			}
		}
		Console.WriteLine(dp[N].Max());
	}
}

public class Scanner
{
	public Scanner() { }
	public string next()
	{
		return Console.ReadLine();
	}
	public int nextInt()
	{
		return int.Parse(next());
	}
	public double nextDouble()
	{
		return double.Parse(next());
	}
	public long nextLong()
	{
		return long.Parse(next());
	}
	public string[] nextArray()
	{
		return next().Split(' ');
	}
	public int[] nextIntArray()
	{
		return Array.ConvertAll(nextArray(), e => int.Parse(e));
	}
	public long[] nextLongArray()
	{
		return Array.ConvertAll(nextArray(), e => long.Parse(e));
	}
	public double[] nextDoubleArray()
	{
		return Array.ConvertAll(nextArray(), e => double.Parse(e));
	}
}