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

typedef long long   signed int LL;
typedef long long unsigned int LU;

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define inc( i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec( i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))

#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define UB upper_bound
#define LB lower_bound
#define PQ priority_queue

#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
#define  FOR(i, v) for(auto i =  v.begin(); i !=  v.end(); ++i)
#define RFOR(i, v) for(auto i = v.rbegin(); i != v.rend(); ++i)

template<typename T> bool setmin(T & a, T b) { if(a <= b) { return false; } else { a = b; return true; } }
template<typename T> bool setmax(T & a, T b) { if(b <= a) { return false; } else { a = b; return true; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

template<typename T> ostream & operator<<(ostream & os, const vector<T> & v) {
	os << "[";
	FOR(it, v) {
		if(it != v.begin()) { os << ", "; }
		os << *it;
	}
	os << "]";
	return os;
}
template<typename F, typename S> ostream & operator<<(ostream & os, const pair<F, S> & p) {
	os << "<" << p.FI << ", " << p.SE << ">";
	return os;
}

// ---- ----

int n, a, x[10];

int main() {
	cin >> n >> a;
	inc(i, n) { cin >> x[i]; }
	
	LL sum = 0;
	inc(i, n) { sum += x[i]; }
	if(sum % n == 0 && sum / n == a) { cout << "YES" << endl; return 0; } else { cout << "NO" << endl; }
	
	
	return 0;
}