using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		long[] dp = Enumerable.Repeat(-1,M+1).Select(x=>(long)x).ToArray();
		dp[0] = 0;
		for(int i=0;i<N;i++){
			for(int j=0;j<=M;j++){
				if(dp[j] == -1)continue;
				if(j + C[i] <= M){
					dp[j + C[i]] = Math.Max(dp[j + C[i]],dp[j] + 1);
				}
			}
		}
		long sum = 0;
		long last = 0;
		for(int i=1;i<=M;i++){
			if(dp[i] != -1){
				if(isPrime(M - i)){
					sum += dp[i];
				}
			}
		}
		last = dp.Max();
		Console.WriteLine(sum + last);
		
		
	}
	
	static bool isPrime(long x){
		if(x<2) return false;
		if(x==2)return true;
		for(long j=2;j*j<=x;j++){
			if(x%j == 0)return false;
		}
		return true;
	}
	
	int M;
	int N;
	int[] C;
	public Sol(){
		M = ri();
		N = ri();
		C = ria();
	}

	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(char sep=' '){return Console.ReadLine().Split(sep);}
	static int[] ria(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>int.Parse(e));}
	static long[] rla(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>long.Parse(e));}
	static double[] rda(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>double.Parse(e));}
}