#include <iostream>
#include <math.h>
using namespace std;

#define Rop(i,N) for(int i=0;i<N;i++)

int main(void){
    long long N,A;
    long long x,sum = 0;

    cin >> N >> A;
    Rop(i,N){cin >> x; sum += x;}

    if(A * N == sum)cout << "YES" << endl;
    else cout << "NO" << endl;
    return (0);
}