#include<bits/stdc++.h>
 using namespace std;
#define INF 1000000000
#define REP(i,n) for(int (i)=0;(i)<(int)(n);(i)++)
typedef long long LL;
int N;
LL x[100];
LL a;
int main(){
    cin>>N>>a;
    LL ans=0;
    REP(i,N){
        cin>>x[i];
        ans+=x[i];
    }
    if(ans%N==0){
       if(ans/N==a){
          cout<<"YES"<<endl;
       }else{
          cout<<"NO"<<endl;
       }
    }else{
       cout<<"NO"<<endl;
    }
    
    return 0;
}