#include <bits/stdc++.h> 
using namespace std;map<int,int> mp;int n,c,ans;int main() {cin>>n>>c;for(int i=1;i<=n;i++){int x;cin>>x;mp[x]++;}for(auto i:mp){if(mp.count(i.first-c))ans+=i.second*mp[i.first-c];}cout<<ans;return 0;}