#include <stdio.h>
int main(void){
	int n;
    int a;
	int x;
	long sum = 0;
    double ave;
	
	scanf("%d %d",&n,&a);
    for(int i = 0; i < n; i++){
        scanf("%d",&x);
        sum += x;
    }
    ave = (double)sum / n;
    
    if(ave == a){
        printf("YES\n");
    }else{
        printf("NO\n");
    }
	
	return 0;
}