#include <bits/stdc++.h>
using namespace std;
int main(){
	int i,n,j,m,l=0,k;
	cin>>n;
	cin>>k;
	int a[n];
	for(i=1;i<=n;i++){
		cin>>a[i-1];
         }
	for(i=1;i<=n-1;i++){
		for(j=1;j<=n-i;j++){
			if(a[j-1]>a[j])
			swap(a[j-1],a[j]);
	    }
	}
	m=a[n-k]-a[k-1];
	l=0;
	if(m==1||m==2) l=0;
	else
		{for(i=2;i<m;i++){
		if(m%i==0) {l=1;break;}
		}}
	if(l==0)
	cout<<"yes"<<endl;
	else
	cout<<"no"<<endl;
	cout<<m;
	return 0;
	}
/**************************************************************
	Problem: 1242
	User: fzy001
	Language: C++
	Result: Wrong Answer
****************************************************************/