import java.util.*;

public class Main {
    static int t;
    static int n;
    static int[] tArr;
    static int[] vArr;
    static int[][] dp;
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		t = sc.nextInt();
		n = sc.nextInt();
		tArr = new int[n + 1];
		for (int i = 1; i <= n; i++) {
		    tArr[i] = sc.nextInt();
		}
		vArr = new int[n + 1];
		for (int i = 1; i <= n; i++) {
		    vArr[i] = sc.nextInt();
		}
		dp = new int[n + 1][t + 1];
		System.out.println(dfw(n, t));
   }
   
   static int dfw(int idx, int time) {
       if (idx == 0) {
           return 0;
       }
       if (dp[idx][time] != 0) {
           return dp[idx][time];
       }
       int value = vArr[idx];
       int total = 0;
       for (int i = 0; i * tArr[idx] <= time && value > 0; i++) {
           dp[idx][time] = Math.max(dp[idx][time], total + dfw(idx - 1, time - i * tArr[idx]));
           total += value;
           value /= 2;
       }
       return dp[idx][time];
   }
}