#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001


int main(){
	int n;
	cin>>n;
	vector<pair<long long,long long>> a(n);
	rep(i,n){
		cin>>a[i].first>>a[i].second;
	}
	sort(a.begin(),a.end());
	map<vector<long long>,long long> mp;
	long long ans = 0;
	rep(i,n){
		for(int j=i+1;j<n;j++){
			long long dx = a[j].first-a[i].first;
			long long dy = a[j].second-a[i].second;
			long long cx = a[i].first + a[j].first;
			long long cy = a[i].second + a[j].second;
			
			long long g = gcd(abs(dx),abs(dy));
			dx /= g;
			dy /= g;
			mp[{dx,dy,cx,cy}]++;
			swap(dx,dy);
			dx *= -1;
			if(dx<0){
				dx *= -1,dy *= -1;
			}
			else if(dx==0){
				dy = abs(dy);
			}
			ans += mp[{dx,dy,cx,cy}];
		}
	}
	
	cout<<ans<<endl;
	
	return 0;
}