#include <iostream>

using namespace std;

int main(void){
    int n;
    long long a;
    cin >> n >> a;
    long long x = 0;
    for(int i = 0; i < n; i++){
        long long tmp = 0;
        cin >> tmp;
        x += tmp;
    }
    double ave = (double)x / (double)n;
    printf("%s\n",(ave == (double)a) ? "YES" : "NO");
    return 0;
}