#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    
    int n;
    long long a;
    cin >> n >> a;
    
    long long s = 0;
    for ( int i = 0; i < n; i++ ) {
        long long x;
        cin >> x;
        s += x;        
    }
    
    cout << ( s == a*n ? "YES" : "NO" ) << endl;
    
    
    return 0;
}