#include <iostream>
#include <cstdio>
using namespace std;
long int n,c;
long int i,j;
long int ans=0;
long int num[200001];
int main()
{
	freopen("dec.in","r",stdin);
	freopen("dec.out","w",stdout);
	cin>>n>>c;
	for(i=0;i<n;i++)
		cin>>num[i];
	for(i=0;i<n;i++)
	{
		for(j=0;j<n;j++)
		{
			if(i!=j)
			{
				if(num[i]-num[j]==c)
					ans++;
			}
		}
	}
	cout<<ans;
	return 0;
}