#include <bits/stdc++.h>

using namespace std;

inline void Open(const string Name) {
    #ifndef ONLINE_JUDGE
        (void)!freopen((Name + ".in").c_str(), "r", stdin);
        (void)!freopen((Name + ".out").c_str(), "w", stdout);
    #endif
}

unordered_map <double, int> H;

int x[1001], y[1001];
int N, ans;

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

    Open("trapez");

    cin >> N;
    for(int i = 1;i <= N;i++)
        cin >> x[i] >> y[i];


    for(int i = 1;i < N;i++)
        for(int j = i + 1;j <= N;j++) {
            double val = (double)(y[j] - y[i]) / (x[j] - x[i]);
            if(H.find(val) != H.end()) {
                ans += H[val];
                H[val]++;
            } else {
                H.insert({val, 1});
            }
        }


    cout << ans;

    return 0;
}