#include<stdio.h>
typedef long long int ll;

int main(void){
    int n,a;
    scanf("%d%d", &n,&a);

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

    if(sum/n == a){
        printf("YES\n");
    }else{
        printf("NO\n");
    }
}