#include<iostream>
#include<iomanip>
#include<cmath>
#include<string>
#include<algorithm>
#include<vector>
#include<math.h>

using namespace std;
int main(){
    int n; long long sum = 0; long x; 
long ave;
cin >> n >> ave;
    for(int i = 0; i < n; i++){
        cin >> x;
        sum = sum + x;
    }
    if(sum / n == ave){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
    return 0;
}