#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;
    }
};


set<pair<pair<int, int>, pair<int, int>>> mp;
coords puncte[LIM + 9];

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++) {
            pair<pair<int, int>, pair<int, int>> s;

            s.first.first = abs(puncte[i].x - puncte[j].x);
            s.first.second = 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.second.first = s.first.first / 2 + xs;
            s.second.second = s.first.second / 2 + ys;

            //cout << s.second.first << ' ' << s.second.second << ' ' << s.len;

            if (mp.count({{s.first.second, s.first.first}, s.second})) {
                ans++;
            }

            mp.insert(s);
        }
    }

    fout << ans;

    return 0;
}