import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		int[] u = new int[n];
		for (int i = 0; i < n; i++) {
			u[i] = sc.nextInt();
		}
		int[] t = new int[m];
		for (int i = 0; i < m; i++) {
			t[i] = sc.nextInt();
		}
		sc.close();

		int x = 100000;
		boolean[] dp = new boolean[x + 1];
		dp[0] = true;
		for (int i = 0; i < m; i++) {
			for (int j = x - t[i]; j >= 0; j--) {
				if (dp[j]) {
					dp[j + t[i]] = true;
				}
			}
		}

		boolean[] ans = new boolean[x * 2 + 1];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < dp.length; j++) {
				if (dp[j]) {
					ans[j + u[i]] = true;
				}
			}
		}
		int cnt = 0;
		for (int i = 0; i < ans.length; i++) {
			if (ans[i]) {
				cnt++;
			}
		}
		System.out.println(cnt);
	}
}