#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, len;

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++)
            H[(double)(y[j] - y[i]) / (x[j] - x[i])]++;

    int ans = 0;
    for(auto &it : H) {
        ans += (1LL * it.second * (it.second - 1) / 2);
    }

    cout << ans;

    return 0;
}