#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,i,j,k,m;
	cin>>n;
	cin>>k;
	int a[10000];
	for(i=0;i<n;i++){
		cin>>a[i];
	}
	for(i=1;i<n;i++){
		for(j=1;j<n-i;j++){
			if(a[j]<a[j+1])
			swap(a[j],a[j+1]);
		}
	}
	bool p=0;
	m=a[k-1]-a[n-k];
	if(m!=1||m!=2){
		for(i=2;i<m;i++){
			if(m%i==0){
				p++;
				break;
			}
		}
	}
	else{
		p=0;
	}
	if(p==0)
	cout<<"YES"<<endl;
	else
	cout<<"NO"<<endl;
	cout<<m; 
	return 0;
}

/**************************************************************
	Problem: 1242
	User: houshanglin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/