#include <iostream>
using namespace std;
int main(void){
    // Here your code !
    double N,A,res = 0;
    cin >> N >> A;
    
    for(int i = 0 ; i < N; i++){
        long long int a;
        cin >> a;
        res += a;
    }
    
    if( A == res / N){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
    
}