#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: wengsihan
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/