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

int main(void)
{

   int n, a;
   cin >> n >> a;
   int sum = 0;
   int tmp;
   for(int i = 0; i < n; i++)
    {
        cin >> tmp;
        sum += tmp;
    }
    if(a*n == sum)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;
   return 0;
}