#include<iostream>
#include<vector>
#include<string>
#include<cstdio>
using namespace std;
int main(){
    long double n,a,hoge=0,x;
    cin >> n >> a;
    for(int i=0;i<n;i++){
        cin >> x;
        hoge+=x;
    }
    if(hoge/n==a)   cout << "YES" << endl;
    else    cout << "NO" << endl;
    return 0;
}