#include<iostream>
using namespace std;
int main(){ 
    int n,a; 
    cin>>n>>a; 
    int X=0;
    for(int i=0;i<n;i++){
        int x;
        cin>>x;
        X+=x;
    }
    if(X%n==0&&X/n==a){
        cout<<"YES"<<endl;
        return 0;
    }
    cout<<"NO"<<endl;
}