#include <stdio.h>
int main(){
    //input
    int n,a;
    scanf("%d %d",&n,&a);

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

    //output
    if (double(total)/n == a){
        printf("YES\n");
    }else{
        printf("NO\n");
    }
    return 0;
}