#include <bits/stdc++.h>
using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    vector<pair<long long,long long>> XY(N);
    for(auto &[x,y] : XY) cin >> x >> y,x *= 2, y *= 2;

    map<pair<long long,long long>,map<pair<long long,long long>,long long>> M;
    for(int i=0; i<N; i++) for(int k=i+1; k<N; k++){
        auto[x1,y1] = XY.at(i);
        auto[x2,y2] = XY.at(k);
        if(x1 > x2) swap(x1,x2),swap(y1,y2);

        long long mx = (x1+x2)/2,my = (y1+y2)/2;
        if(x1 == x2) M[{mx,my}][{0,1}]++;
        else if(y1 == y2) M[{mx,my}][{1,0}]++;
        else{
            long long dx = abs(x2-x1),dy = abs(y2-y1),g = gcd(dx,dy);
            M[{mx,my}][{(x2-x1)/g,(y2-y1)/g}]++;
        }
    }

    long long answer = 0;
    for(auto &[ig,V] : M){
        for(auto &[k,v] : V){
            auto &[x,y] = k;
            if(x < 0 || y == 0) continue;
            if(x == 0) answer += v*V[{1,0}];
            else answer += v*V[{y,-x}];
        }
    }
    cout << answer << endl;
}