#include <bits/stdc++.h>
using namespace std;
int main(){
	int N, M;
	cin >> N >> M;
	vector<int> A(N);
	for (int i = 0; i < N; i++){
		cin >> A[i];
	}
	for (int i = 0; i < N; i++){
		A.push_back(A[i] + M);
	}
	if (M % 2 == 1){
		cout << 0 << endl;
		return 0;
	}
	long long ans = 0;
	for (int i = 0; i < N; i++){
		auto it = lower_bound(A.begin(), A.end(), A[i] + M / 2);
		if (it != A.end() and *it == A[i] + M / 2){
			ans += it - A.begin() - i - 1;
		}
	}
	cout << ans << endl;
}