#include<stdio.h>
int main()
{   int n,a,b,count,i;
    scanf("%d\n",&n);
    scanf("%d",&a);
    for(i=0;i<n;i++){
        scanf("%d ",&b);
        while(i==n)
        {scanf("%d",&b);}
        if(a-b==1||b-a==1){
        count++;}
    }
    printf("%d",count);
    return 0;
}