#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <map>
#include <cmath>
using namespace std;

bool Prime[10001];
int Num[10001];

int main(){
	for (int i = 0; i < 10001; i++)Prime[i] = true;
	Prime[0] = false;
	Prime[1] = false;
	for (int i = 2; i < 10001; i++){
		if (Prime[i]){
			for (int j = i * 2; j < 10001; j+=i){
				Prime[j] = false;
			}
		}
	}

	int m, n; cin >> m >> n;
	vector<int>C;
	for (int i = 0; i < n; i++){
		int c; cin >> c;
		if(c<=m)C.push_back(c);
	}
	for (int j = 0; j < C.size(); j++)Num[C[j]] = 1;
	for (int i = 0; i < m; i++){
		for (int j = 0; j < C.size(); j++){
			if (Num[i] == 0)continue;
			Num[i + C[j]] = max(Num[i] + 1, Num[i + C[j]]);
		}
	}

	int sum = 0;
	int maxcnt = 0;
	for (int i = 0; i <= m; i++){
		maxcnt = max(maxcnt, Num[i]);
	}
	for (int i = 0; i < m; i++){
		if (Prime[m - i]){
			sum += Num[i];
		}
	}
	cout << sum + maxcnt << endl;

	return 0;
}