#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;

int main(){
    long long n, a, temp, sumx = 0;
    cin >> n >> a;
    for (int i = 0; i < n; i++){
        cin >> temp;
        sumx += temp;
    }
    cout << ((a == (double)sumx/n) ? "YES" : "NO") << endl;
}