#include<bits/stdc++.h>
using namespace std;
int big,n,c,s;
int a[100000000],b[100000000];
int main(){
    cin>>n>>c;
    for(int i=1;i<=n;i++){
        cin>>a[i];
        b[a[i]]++;
        if(a[i]>big)
			big=a[i];
    }
    for(int i=1;i<=big;i++){
        if((b[i]>0)&&(b[i+c]>0)) 
			s=s+b[i]*b[i+c];
    }
    cout<<s;
    return 0;
}