#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstdlib>
#include <cstring>

using namespace std;

#define FOR(i,a,b) for (int i = (a); i < (b); i++)
#define REP(i,n) FOR(i,0,n)

typedef long long ll;

int main(){
	int n, a;
	
	cin >> n >> a;
	
	ll sum = 0;
	
	REP(i,n){
		ll num;
		
		scanf("%lld", &num);
		
		sum += num;
	}
	
	if ((double)sum/(double)n == (double)a) cout << "YES" << endl;
	else cout << "NO" << endl;
	
	return 0;
}