#include <bits/stdc++.h>

using namespace std;

const int LIM = 1e3, INM = 1e6, INM2 = 1e6;
const long long int BINM = 1e10, INF = 1e18 + 67;


ifstream fin ("patrate3.in");
ofstream fout ("patrate3.out");

struct coords {
    long long int x, y;
    bool operator<(const coords& other) const {
        if (x != other.x)
            return x < other.x;
        return y < other.y;
    }
};

struct segment {
    int dx, dy;
    int mx, my;
    bool operator<(const segment& other) const {
        if (dx != other.dx)
            return dx < other.dx;
        if (dy != other.dy)
            return dy < other.dy;
        if (mx < other.mx)
            return mx < other.mx;
        return my < other.my;
    }
};

map<segment, int> mp;
coords puncte[LIM + 9];
vector<segment> segmente;

int main() {

    int n;
    fin >> n;
    for (int i = 1; i <= n; i++) {
        string nr;
        char ch;

        fin >> nr;
        int p = 0;
        for (int i = 0; i < nr.size(); i++) {
            if (nr[i] == '.')
                p = i;
        }
        string newnr{};
        for (int i = 0; i < p; i++) {
            newnr += nr[i];
        }
        for (int i = p + 1; i < nr.size(); i++) {
            newnr += nr[i];
        }

        long long int x = atoi(newnr.c_str()) * 10ll;

        fin >> nr;
        p = 0;
        for (int i = 0; i < nr.size(); i++) {
            if (nr[i] == '.')
                p = i;
        }
        newnr = "";
        for (int i = 0; i < p; i++) {
            newnr += nr[i];
        }
        for (int i = p + 1; i < nr.size(); i++) {
            newnr += nr[i];
        }
        long long int y = atoi(newnr.c_str()) * 10ll;

        puncte[i] = {x, y};
    }

    int ans = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = i + 1; j <= n; j++) {
            segment s;

            s.dx = abs(puncte[i].x - puncte[j].x);
            s.dy = abs(puncte[i].y - puncte[j].y);

            long long int xs = puncte[i].x < puncte[j].x ? puncte[i].x : puncte[j].x;
            long long int ys = puncte[i].y < puncte[j].y ? puncte[i].y : puncte[j].y;

            s.mx = s.dx / 2 + xs;
            s.my = s.dy / 2 + ys;

            //cout << s.mx << ' ' << s.my << ' ' << s.len;

            if (mp.count({s.dy, s.dx, s.mx, s.my})) {
                ans += mp[{s.dy, s.dx, s.mx, s.my}];
            }

            segmente.push_back(s);
            mp[s] += 1;
        }
    }

    fout << ans;

    return 0;
}