#include <cstdio>
#include <hash_map.h>
#define maxn 8200
using namespace std;

hash_map<int,int, hash<int> >H;

int main()
{
	int x[maxn], n;
	freopen("tri.in", "r", stdin);
	//scanf("%d\n", &n);
	n=8000;
	int i, j;
	for(i=1;i<=n;i++)x[i]=i+78907;// scanf("%d ", &x[i]);
	for(i=1;i<=n;i++) H[x[i]]++;
	
	int t, nr=0;
	for(i=1;i<n;i++)
		for(j=i+1;j<=n;j++)
		{
			if((x[i]+x[j])%2==1) continue;
			t=(x[i]+x[j])/2;
			if(x[i]==t || x[j]==t) continue;
			nr+=H[t];
		}
	//	printf("%d\n", nr);
	
	return 0;
}