#include <iostream>
using namespace std;

int main(void){
    int n = 0;
    int a = 0;
    int i = 0;
    long long num = 0;
    int  *x;
    long long res = 0;
    
    cin >> n >> a;
    x = new int[n];
    for(i=0;i<n;i++){
        cin >> x[i];
        num += x[i];
    }
    //res = (long long)((float)num/(float)n);
    res = (long long)(num/n);

    if(res - a == 0){
        cout << "YES\n";
        //cout << "res: " << res << "\n" << "a: " << a << "\n" << "YES\n";
    }else{
        cout << "NO\n";
        //cout << "res: " << res << "\n" << "a: " << a << "\n" << "NO\n";
    }
    return (0);
}