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

public class Program {
	public static void main(String[] args) {
		new Magatro().solve();
	}
}

class Magatro {
	private int m, n;
	private int[] c;
	private int[] dp;
	private List<Integer> primes;

	private void scan() {
		Scanner scanner = new Scanner(System.in);

		m = scanner.nextInt();
		n = scanner.nextInt();
		c = new int[n];

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

		// scanner.close();
	}

	private void primeCalc() {
		primes = new ArrayList<Integer>();
		boolean[] bs = new boolean[m + 1];
		bs[0] = true;
		bs[1] = true;
		for (int i = 2; i * i <= m; i++) {
			if (!bs[i]) {
				for (int j = i * 2; j <= m; j += i) {
					bs[j] = true;
				}
			}
		}
		for (int i = 2; i <= m; i++) {
			if (!bs[i]) {
				primes.add(i);
			}
		}

	}

	public void solve() {
		scan();

		dp = new int[m + 1];

		for (int i = 0; i <= m; i++) {
			dp[i] = -1;
		}

		dp[m] = 0;

		for (int i = m; i >= 0; i--) {
			if (dp[i] == -1) {
				continue;
			}

			for (int j : c) {
				if (i - j < 0) {
					continue;
				}

				dp[i - j] = Math.max(dp[i - j], dp[i] + 1);
			}
		}

		primeCalc();
		int ans = 0;
		for (int i : primes) {
			if (dp[i] == -1) {
				continue;
			}

			ans += dp[i];
		}

		int max = 0;
		for (int i : dp) {
			max = Math.max(max, i);
		}
		ans += max;

		System.out.println(ans);
	}
}