#include <bits/stdc++.h>
using namespace std;
const int N=4e6+10; 
inline void read(int &x)
{
	int cnt=0;
	char c=getchar();
	while (!('0'<=c && c<='9')) c=getchar();
	while ('0'<=c && c<='9') cnt=cnt*10+(c-'0'),c=getchar();
	x=cnt;
}
int x,n,c,ans[10010],tot=0;
long long mp[N],a[N],b[N];
void solve1()
{
	long long ret=0;
	for (int i=0;i<c*2;i++) a[i]=a[(i-1 ? i-1 : 0)]+mp[i];
	for (int i=0;i<c*2;i++) b[i]=b[(i-1 ? i-1 : 0)]+mp[i]*a[i+c/2-1];
	for (int i=1;i<=c;i++) ret+=mp[i]*(b[i+c/2-1]-b[i]-a[i+c/2]*(a[i+c/2-1]-a[i]));
	cout<<ret/3; 
}
void solve2()
{
	long long ret=0;
	for (int i=0;i<c*2;i++) a[i]=a[(i-1 ? i-1 : 0)]+mp[i];
	for (int i=0;i<c*2;i++) b[i]=b[(i-1 ? i-1 : 0)]+mp[i]*a[i+c/2];
	for (int i=1;i<=c;i++) ret+=mp[i]*(b[i+c/2]-b[i]-a[i+c/2]*(a[i+c/2]-a[i]));
	cout<<ret/3;
}
int main() {
	freopen("Triplets.in","r",stdin);
	freopen("Triplets.out","w",stdout); 
	read(n),read(c);
	for (int i=1;i<=n;i++) read(x),mp[x]++,mp[x+c]++;
	if (c%2==0) solve1();
	else solve2();
	return 0;
}