#include<bits/stdc++.h>
using namespace std;
int main()
{
	int N,a[10],i,K,j=0,m=0,p,c=0;
	cin>>N>>K;
	for(i=0;i<N;i++){
		cin>>a[i];	
	}
	for(i=1;i<=N-1;i++){
		for(j=1;j<=N-i;j++){
			if(a[j-1]<a[j])
				swap(a[j],a[j-1]); 
		}
	}j=K-1;
	c=N-K;
	m=a[j]-a[c];
	int q=0;
	for(i=2;i<m;i++){
		if(m%i==0&&m!=2){
			q=1;
			break;
		}
	}
	if(q==1)
	cout<<"no"<<endl;
	else
	cout<<"yes"<<endl;
	cout<<m;
	return 0;
}
/**************************************************************
	Problem: 1242
	User: houshanglin
	Language: C++
	Result: Wrong Answer
****************************************************************/