84分，1个WA，1个MLE

#include <bits/stdc++.h>
using namespace std;
map<int,int> a;
int maxn=-1e9,minn=1e9,sum;
int main()
{
	int n,c;
	cin>>n>>c;
	for(int i=1;i<=n;i++)
	{
		int x;
		cin>>x;
		a[x]++;
		maxn=max(maxn,x);
		minn=min(minn,x);
	}
	for(int i=minn;i<=maxn;i++)
		if(a[c+i]>0)
			sum+=a[i]*a[c+i];
	cout<<sum;
	return 0;
}