#include <cstdio>
#include <algorithm>

using namespace std;

const float eps = 1e-4;

template <typename T>
T ABS(T X) { return X < 0 ? -X : X; }

struct coor {
	float x, y; 
	coor() {;}
	coor(const float a, const float b) { x = a; y = b; }
};

bool operator<(const coor &a, const coor &b) {
	return a.x + eps < b.x || (ABS(a.x - b.x) < eps && a.y + eps < b.y);
}

coor operator+(const coor &a, const coor &b) {
	return coor(a.x + b.x, a.y + b.y);
}

coor operator/(const coor &a, const int k) {
	return coor(a.x / k, a.y / k);
}

const int NMAX = 1024;

int N;
coor A[NMAX];
int cnt;

void read() {
	FILE *fin = fopen("patrate3.in", "rt");
	int i;

	fscanf(fin, " %d", &N);

	for (i = 0; i < N; ++i)
		fscanf(fin, " %f %f", &A[i].x, &A[i].y);

	fclose(fin);
}

void count() {
	int i, j;
	coor c1, c2, mij, d;

	for (i = 0; i < N; ++i)
		for (j = i + 1; j < N; ++j) {

			mij = (A[i] + A[j]) / 2;
			d = coor( mij.x - A[i].x, mij.y - A[i].y );

			c1 = coor(mij.x + d.y, mij.y - d.x);
			c2 = coor(mij.x - d.y, mij.y + d.x);

			if (binary_search(A + i + 1, A + N, c1) && binary_search(A + i + 1, A + N, c2))
				++cnt;
		}
}

void write() {
	FILE *fout = fopen("patrate3.out", "wt");

	fprintf(fout, "%d\n", cnt);

	fclose(fout);
}

int main() {
	
	read();

	sort(A, A + N);

	count();

	write();

	return 0;
}