#include <stdio.h>

int main(){
	double val,ans;
	scanf("%lf%lf",&val,&ans);
	
	double num = 0;
	double sum = 0;
	for(int i = 0;i < val;i++){
		scanf("%lf",&num);
		sum += num;
	}
	if((sum / val) == ans){
		printf("YES");
	}else{
		printf("NO");
	}
}