```cpp
#include<bits/stdc++.h>
using namespace std;
int num[20000005],tot;
map<long long,long long>m;
int main()
{
int n,c,t;
scanf("%d%d",&n,&c);
for(int i=1;i<=n;i++)
{
scanf("%d",&t);
m[t]++;
num[i]=t;
}
for(int i=1;i<=n;i++)
if(m[num[i]+c]!=0) tot+=m[num[i]+c];
printf("%d",tot);
return 0;
}
```
已AC
by a2426632670 @ 2017-11-04 14:14:05