#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << (x) << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010


int main(){
  int n,a;
  int x;
  ll sum;
  
  scanf("%d%d",&n,&a);

  sum = 0;
  
  for(int i=0;i<n;i++){
    scanf("%d",&x);
    sum += x;
  }

  if((ll)a*n == sum){
    puts("YES");
  }else{
    puts("NO");
  }
  
  
  return 0;
}