#include <stdio.h>

int main(){
    long long int N, a, i;
    long long int num[10], ave, sum = 0;

    scanf("%lld %lld\n", &N, &a);
    for(i = 0; i < N; i++){
        scanf("%lld", &num[i]);
        sum += num[i];
    }
    ave = sum/N;
    //printf("a = %lld ave = %lld\n", a, ave);
    if(a == ave && sum%N == 0){
        printf("YES\n");
    }else{
        printf("NO\n");
    }

    return 0;

}