#include    <bits/stdc++.h>
#define     NMAX 1010

using namespace std;

ifstream fin("trapez.in");
ofstream fout("trapez.out");

int N, a[NMAX], b[NMAX], sol;

vector< pair <int , int> > v;

void read()
{
    fin >> N;
    for(int i = 1; i <= N; i++)
    {
        fin >> a[i] >> b[i];
    }
}

void solution()
{
    for(int i = 1; i <= N; i++)
        for(int j = i+1; j <= N; j++)
        {
            int x = a[i] - a[j];
            int y = b[i] - b[j];
            int g = __gcd(x,y);
            v.push_back({y/g,x/g});
        }

    sort(v.begin(),v.end());

    pair<int,int> last=v[0];

    int k = 1;

    for(int i = 1; i < v.size(); i++)
    {
        if(v[i] == last)
            k++;
        else
        {
            sol += (k * (k-1)) / 2;
            k = 1;
        }
        last = v[i];
    }
    fout << sol;
}

int main()
{
    read();
    solution();
    return 0;
}