#include <bits/stdc++.h>
#define  re(i,j,n) for(li i=(j);i<(n);i++)
#define  rep(i,n) re(i,0,(n))
#define  all(a) begin(a),end(a)
#define  pb push_back
using namespace std;
typedef long int li;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<li> vli;
typedef vector<string> vs;


int main()
{
    li n,a,x,sum=0;
    cin>>n>>a;
    rep(i,n) {
        cin>>x;
        sum+=x;
    } 
    if(sum==n*a) cout<<"YES\n";
    else       cout<<"NO\n" ;
    
    return 0;
}