#include <fstream>
#include <unordered_map>
#include <iostream>
using namespace std;

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

    int n;
    int x[1000], y[1000], s = 0;
    unordered_map<double, int> um;
    fin >> n;
    for (int i = 0; i < n; i++) {
        fin >> x[i] >> y[i];
        for (int j = 0; j < i; j++)
            if (x[j] == x[i])
                s += um[-1]++;
            else if (y[j] == y[i])
                s += um[0]++;
            else
                s += um[(double)(y[j] - y[i]) / (x[j] - x[i])]++;
    }

    fout << s;
    fin.close();
    fout.close();
    return 0;
}