import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;


public class Main_yukicoder37 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int t = sc.nextInt();
        int n = sc.nextInt();

        int[] c = new int[n];
        int[] v = new int[n];
        for (int i = 0; i < n; i++) {
        	c[i] = sc.nextInt();
        }
        for (int i = 0; i < n; i++) {
        	v[i] = sc.nextInt();
        }

        int[] dp = new int[t + 1];
        for (int i = 1; i <= n; i++) {
            List<Integer> cc = new ArrayList<>();
            List<Integer> vv = new ArrayList<>();
            int tmpv = v[i - 1];
            int tmpc = c[i - 1];
            int sumv = tmpv;

            while (tmpv > 0) {
            	cc.add(tmpc);
            	vv.add(sumv);

            	tmpc += c[i - 1];
            	tmpv /= 2;
            	sumv += tmpv;
            }

            int m = cc.size();

            for (int j = t; j > 0; j--) {
            	for (int k = 0; k < m; k++) {
            		int tmpvv = vv.get(k);
            		int tmpcc = cc.get(k);

            		if (j - tmpcc >= 0) {
            			dp[j] = Math.max(dp[j], dp[j - tmpcc] + tmpvv);
            		}
        		}
        	}
        }

        System.out.println(dp[t]);

        sc.close();
    }
}