#include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;

int main(){
    int n,a,x,sum = 0; cin >> n >> a;
    rep(i,n){
        cin >> x;
        sum += x;
    }
    if(sum / n == a && sum % n == 0){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
}