#include "bits/stdc++.h"

#include <stdio.h>
#include <math.h>

#include "atcoder/all"
#include <float.h>

//#include <boost/multiprecision/cpp_int.hpp>
//using namespace boost::multiprecision;

using namespace std;
using namespace atcoder;

using ll = long long;
using ull = unsigned long long;
using mint = modint998244353;
using mint2 = modint1000000007;
const double eps = 1e-9;

#define REP(i, n) for (ll i = 0; i < ll(n); ++i)
#define REPI(i, init, n) for (ll i = init; i < ll(n); ++i)
#define REPD(i, init) for (ll i = init; i >=0; --i)
#define REPDI(i, init, n) for (ll i = init; i >=n; --i)
#define REPE(i, c) for (const auto& i : c)
#define TCASE() ll _ttt; cin >> _ttt; while(_ttt--)

using vl = vector<ll>; using vvl = vector<vl>; using vvvl = vector<vvl>;
#define VLI(a, n) vector<ll> a; a.assign(n, 0); for(auto& x : a) cin >> x;
#define DLI(a, n) deque<ll> a; a.assign(n, 0); for(auto& x : a) cin >> x;
#define VSI(a, n) vector<string> a; a.assign(n, ""); for(auto& x : a) cin >> x;
#define VVLI(a, n, m, init) vector<vector<ll>> a(n); for(auto& x : a) x.assign(m, init);
using vd = vector<double>; using pl = pair<ll, ll>; using vpl = vector<pl>;

struct uv { ll u; ll v; ll c; };
#define VUVI(a, n) vector<uv> a; a.assign(n, {0, 0, 1}); for(auto& x : a) {cin >> x.u >> x.v; x.u--; x.v--;}
#define VUVCI(a, n) vector<uv> a; a.assign(n, {0, 0, 0}); for(auto& x : a) {cin >> x.u >> x.v >> x.c; x.u--; x.v--;}
vvl to_edge(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) ret[x.u].push_back(x.v); return ret; }
vvl to_edge_d(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) { ret[x.u].push_back(x.v); ret[x.v].push_back(x.u); } return ret; }

template <class T = long long> using pql = priority_queue<T>;
template <class T = long long> using pqg = priority_queue<T, vector<T>, greater<T>>;
using vm = vector<mint>; using vvm = vector<vm>;

ostream& operator<<(ostream& os, const mint& v) { os << v.val(); return os; }
void yn(bool f) { std::cout << (f ? "Yes" : "No") << endl; };
template<class T> void ov(const T& v) { for (auto it = v.begin(); it != v.end(); it++) { if (it != v.begin()) cout << " "; cout << *it; } };
template<> void ov(const vm& v) { for (auto it = v.begin(); it != v.end(); it++) { if (it != v.begin()) cout << " "; cout << it->val(); } };

const ll llhuge = 1LL << 62; //十分でかいが多少足しても溢れない数値
auto gmax(const auto& a, const auto& b) { return a > b ? a : b; };
auto gmin(const auto& a, const auto& b) { return a < b ? a : b; };
bool chmin(auto& a, const auto& b) { const auto olda = a; a = gmin(a, b); return olda != a; }
bool chmax(auto& a, const auto& b) { const auto olda = a; a = gmax(a, b); return olda != a; }
void sort(auto& v) { std::ranges::sort(v); };
void rev(auto& v) { std::ranges::reverse(v); };
template<class T> auto p_sum(const T& v) { T ret(v.size()); std::partial_sum(begin(v), end(v), ret.begin()); return ret; };
template<class T, class K = T::key_type, class V = T::mapped_type> [[nodiscard]] V myat(const T& mp, const K& key) { return mp.find(key) == mp.end() ? V() : mp.at(key); }
long long ceil(const long long a, const long long b) { return (a + b - 1) / b; }

//分数クラス

template<class T = long long>
class Ratio {
    T gcd(T a, T b) noexcept {
        if (a < 0) a = -a;
        if (b < 0) b = -b;
        while (b != 0) {
            a %= b;
            swap(a, b);
        }
        return a;
    }

public:
    T numer = 0;
    T denom = 1;

    Ratio() {};
    Ratio(const T& _numer, const T& _denom) :
        numer(_numer), denom(_denom) {
        reduce();
    };

    void reduce() noexcept {
        const T g = Ratio<T>::gcd(numer, denom);
        numer /= g;
        denom /= g;

        if (denom < T(0)) {
            numer *= -1;
            denom *= -1;
        }
    }

    bool operator<(const Ratio<T>& rhs) const noexcept {
        return (numer * rhs.denom) < (rhs.numer * denom);
    }
    bool operator==(const Ratio<T>& rhs) const noexcept {
        return (numer * rhs.denom) == (rhs.numer * denom);
    }
    bool operator>(const Ratio<T>& rhs) const noexcept {
        return rhs < *this;
    }
    bool operator<=(const Ratio<T>& rhs) const noexcept {
        return !(*this > rhs);
    }
    Ratio<T> operator+(const Ratio<T>& rhs) noexcept {
        return Ratio<T>(numer * rhs.denom + denom * rhs.numer, denom * rhs.denom);
    }
    Ratio<T> operator-(const Ratio<T>& rhs) noexcept {
        return Ratio<T>(numer * rhs.denom - denom * rhs.numer, denom * rhs.denom);
    }
    Ratio<T> operator*(const Ratio<T>& rhs) noexcept {
        return Ratio<T>(numer * rhs.numer, denom * rhs.denom);
    }
};

struct xy { ll x; ll y; };

struct t {
    map<Ratio<>, ll> m;
    ll c_0 = 0;
    ll c_1 = 0;
};

int main() {
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	ll n;
	cin >> n;

    vector<xy> v(n);
    REP(i, n) {
        cin >> v[i].x >> v[i].y;
	}

    map<pl, t> mp;
    REP(i, n) REPI(j, i + 1, n) {
        pair<ll, ll> key = {
            v[j].x + v[i].x, v[j].y + v[i].y
        };
		ll dx = v[j].x - v[i].x;
		ll dy = v[j].y - v[i].y;

        if (dx == 0) {
			mp[key].c_0++;
        }
        else if (dy == 0) {
            mp[key].c_1++;
        }
        else {
			Ratio<> r(dy, dx);
			mp[key].m[r]++;
        }
    }

    ll ans = 0;
    REPE(x, mp) {
        ans += (x.second.c_0 * x.second.c_1);
        REPE(y, x.second.m) {
            if (y.first.numer < 0) continue;
            auto rev = Ratio<>(-y.first.denom, y.first.numer);
            auto it = x.second.m.find(rev);
            if (it == x.second.m.end()) continue;
            ans += y.second * it->second;
        }
	}

    cout << ans << endl;
}