#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int main(void){
int n,a,x[15];
scanf("%d %d",&n,&a);
int sum=0;
    for(int i=0;i<n;i++){
        scanf("%d",&x[i]);
        sum=sum+x[i];
    }
    if((long long int)sum==(long long int)a*n){printf("YES\n");}
    else{printf("NO\n");}
}