#include<bits/stdc++.h>
using namespace std;

int main(){
	cin.tie(0),ios::sync_with_stdio(false);
	int n,a; cin>>n>>a;
	int64_t sum=0;
	for(int i=0;i<n;++i){
		int A; cin>>A;
		sum+=A;
	}
	cout<<(sum==(int64_t)a*n?"YES"s:"NO"s)<<"\n"s;
}