// No.476 正しくない平均
// https://yukicoder.me/problems/no/476
//
#include <iostream>
#include <vector>
#include <numeric>

using namespace std;
string solve(vector<long> &numbers, long n, long a);


int main() {
    long n, a;
    cin >> n >> a;
    vector<long> numbers(n);
    for (auto i = 0; i < n; i++)
        cin >> numbers[i];
    string ans = solve(numbers, n, a);
    cout << ans << endl;
}

string solve(vector<long> &numbers, long n, long a) {
    long total = accumulate(numbers.begin(), numbers.end(), 0L);
    return (total == n * a? "YES": "NO");
}