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

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

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

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