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

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

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