#include<stdio.h>

int main(void){
	unsigned long long int n,a,s=0,m,i;
	scanf("%llu%llu",&n,&a);
	for(i = 1;i <= n;i++){scanf("%llu",&m);s+=m;}
	if(n*a == s){printf("YES\n");}else{printf("NO\n");}
	return 0;
}