#include <bits/stdc++.h>
using namespace std;
const int N = 1010;
struct Point {
    double x, y;
    Point() {}
    Point(double a, double b) { x = a; y = b; }
    void input() { scanf("%lf%lf", &x, &y); }
    friend Point operator+(const Point &a, const Point &b) { return {a.x + b.x, a.y + b.y}; }
    friend Point operator-(const Point &a, const Point &b) { return {a.x - b.x, a.y - b.y}; }
    friend Point rotate(const Point &a, const Point &b) { // 逆转角
        return {a.x * b.x - a.y * b.y, a.x * b.y + a.y * b.x};
    }
} P[N];
unordered_map<double, bool> v;
int main() {
    int n; scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        P[i].input();
        v[P[i].x * 1e10 + P[i].y] = 1;
    }
    int ans = 0;
    for (int i = 1; i < n; i++)
        for (int j = i + 1; j <= n; j++) {
            Point p1 = P[i], p2 = P[j], p3, p4;
            p3 = p2 + rotate(p2 - p1, Point{0, 1});
            p4 = p1 + rotate(p2 - p1, Point{0, 1});
            if (v[p3.x * 1e10 + p3.y] && v[p4.x * 1e10 + p4.y]) ans++;
            
            p3 = p2 + rotate(p2 - p1, Point{0, -1});
            p4 = p1 + rotate(p2 - p1, Point{0, -1});
            if (v[p3.x * 1e10 + p3.y] && v[p4.x * 1e10 + p4.y]) ans++;
        }
    printf("%d\n", ans / 4);
    return 0;
}