#include <bits/stdc++.h>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
int n,i,j;
long long sol;
struct punct{
    int x,y;   
}v[1005];
map <pair<int,int>, int> mp;
punct simp(punct a){
    int aux = __gcd(abs(a.x), abs(a.y));
    if(a.y < 0)
        a.y = -a.y, a.x = -a.x;
    return {a.x/aux, a.y/aux};
}
pair<int,int>getD(punct a, punct b){
    punct aux = {b.x-a.x, b.y-a.y};
    aux = simp(aux);
    return make_pair(aux.x, aux.y);
}
int main(){
    fin>>n;
    for(i=1;i<=n;i++)
        fin>>v[i].x>>v[i].y;
    for(i=1;i<=n;i++){    
        for(j=i+1;j<=n;j++){
            mp[getD(v[i], v[j])]++;
        }
    }
    for(auto &[x,y]:mp){    
        sol = sol+y*(y-1)/2;
    }
    fout<<sol;
    return 0;
}