#include <iostream>
using namespace std;
int main(){
    long long a,b;cin>>a>>b;
    long long sm = 0;
    for(int i = 0; a > i; i++){
        long long k;cin>>k;
        sm += k;
    }
    if((sm%a) || sm/a != b){
        cout << "NO" << endl;
    }else{
        cout << "YES" << endl;
    }
}