import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int T = sc.nextInt();
		final int N = sc.nextInt();
		
		int[] cs = new int[N];
		int[] vs = new int[N];
		for(int i = 0; i < N; i++){
			cs[i] = sc.nextInt();
		}
		for(int i = 0; i < N; i++){
			vs[i] = sc.nextInt();
		}
		
		int[] DP = new int[T + 1];
		Arrays.fill(DP, -1);
		DP[0] = 0;
		
		for(int i = 0; i < N; i++){
			
			for(int j = T; j >= 0; j--){
				for(int value = vs[i], sum_value = vs[i], time = j + cs[i]; value > 0 && time <= T; value /= 2, sum_value += value, time += cs[i]){
					DP[time] = Math.max(DP[time], DP[j] + sum_value);
				}
			}
		}
		
		System.out.println(Arrays.stream(DP).max().getAsInt());
	}

}