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