#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <valarray>
#include <vector>

#define N 1000
#define re(i,n) for(int i=0;i<(n);i++)
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define fe(i,n,f) for_each(i,n,f)
#define bw(a,b,c) (((a)<=(b))&&((b)<=(c)))
using namespace std;

typedef long long ll;

bool c(pair<int,int> a){
	return a.second==1;
}
int main(void){
	int n,a;
	cin>>n>>a;
	valarray<ll> k(n);
	re(i,n)cin>>k[i];
	if(k.sum()%k.size()!=0)cout<<"NO"<<endl;
	else if(k.sum()/k.size()==a)cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	return 0;
}