#include <bits/stdc++.h>

using namespace std;

ifstream fin("patrate3.in");
ofstream fout("patrate3.out");
struct Punct {
    double x, y;

    Punct(int _x = 0, int _y = 0) {
        x = _x;
        y = _y;
    }

    bool operator<(const Punct &p) const {
        return x < p.x || (x == p.x && y < p.y);
    }
} p[1002];
set<Punct> s;
int n, i, j, rasp;
double x, y;

int main() {
    fin >> n;
    for(i = 1; i <= n; i++) {
		fin >> x >> y;

		x = round(x * 10000);
		y = round(y * 10000);

		p[i] = Punct(x, y);
		s.insert(p[i]);
	}

	for(i = 1; i < n; i++) {
        for(j = i + 1; j <= n; j++) {
			int mijx = (p[i].x + p[j].x) / 2;
			int mijy = (p[i].y + p[j].y) / 2;

			int cantx = mijx - p[i].x;
			int canty = mijy - p[i].y;

			Punct p1(mijx - canty, mijy + cantx);
			Punct p2(mijx + canty, mijy - cantx);

			if(s.find(p1) != s.end() && s.find(p2) != s.end()) rasp++;
		}
	}
	fout << rasp / 2;

    return 0;
}