C++ :

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>

using namespace std ;

int n,m;
int a[21];
int t = 0;
int ans = 0;

void in();
void serch(int x,int k);
bool judge(int x);

int main()
{
	//freopen("select.in","r",stdin);
	//freopen("select.out","w",stdout);
	in();
	serch(0,m);
	cout << ans << endl;
	return 0;
}

void in()
{
	cin >> n >> m ;
	for (int i = 1;i<=n;i ++ )
	{
		cin >> a[i];
	}
}

void serch(int x,int k)
{
	if (k == 0)
	{
		if (judge(t)) ans ++ ;
		return;
	}
	for (int i = x+1;i <= n-k+1;i ++ )
	{
		t+=a[i];
		serch(i,k-1);
		t-=a[i];
	}
}

bool judge(int x)
{
	if (x == 1)return false;
	if (x == 2)return true;
	int temp = floor(sqrt(x + 1));
	for (int i = 2 ;i <= temp ; i ++ )
	{
		if (x % i == 0) return false;
	}
	return true;
}