#include <iostream>
#include <string>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;

int main() {
	int n, a, xi;
	double ans = 0;
	
	scanf("%d %d", &n, &a);
	for (int i = 0; i < n; i++)
	{
		scanf("%d", &xi);
		ans += xi;
	}

	if (double(a) == ans / n) printf("YES\n");
	else printf("NO\n");

	return 0;
}