#include<bits/stdc++.h>
//#include<boost/multiprecision/cpp_int.hpp>
//using namespace boost::multiprecision;
using namespace std;
using ll = int64_t;
using pii = pair<int, int>;
#define rep(i,n) for(int i=0; i<(int)n; i++)
#define llrep(i,n) for(ll i=0; i<(ll)n; i++)
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end()) //sortしてから使う
#define INF 2147483647
#define LLINF 9223372036854775807LL
#define fi first
#define se second
#define kiriage(x,y) (((x)+(y)-1)/(y))
typedef vector<int> vi;
typedef vector<ll> vll;

int main(){
	ll n,a; cin>>n>>a;
	ll sum = 0;
	rep(i,n){
		ll x; cin>>x;
		sum += x;
	}
	cout << (sum==a*n? "YES":"NO") << endl;
}