#include<stdio.h>
main(){
    int N,A;
    scanf("%d%d",&N,&A);
    int sum = 0;
    for(int i = 0;i < N;i++){
        int x;
        scanf("%d",&x);
        sum += x;
    }
    if((sum%N)){printf("NO\n");return 0;}
    printf("%s\n",A==(sum/N)?"YES":"NO");
}