#include <bits/stdc++.h>

using namespace std;
const int N = 200010;
typedef long long LL;
unordered_map<int, int> _map;
int a[N];
int n;
int c;
LL ans;

int main() {
    cin >> n >> c;
    for (int i = 1; i <= n; i++)cin >> a[i], _map[a[i]]++;
    for (int i = 1; i <= n; i++)ans += _map[a[i] - c];
    cout << ans << endl;
    return 0;
}