#include <stdio.h>
#include <algorithm>
#include <math.h>
#define ABS(a) ( (a) < 0 ? -(a) : (a) )
#define NMAX 1024
#define EPS 1e-4
using namespace std;
typedef struct { double x, y; } per;
per P[NMAX], punct, punct1, punct2;
int i, j, N, M;
int Sol;
int ok1, ok2;
double a, b;
double mx, my, dx, dy, x3, x4, y3, y4;
int cmp_c(double x, double y)
{
if (fabs(x-y) < EPS) return 0;
if (x < y) return -1;
return +1;
}
int cmp(per A, per B)
{
if (cmp_c(A.x, B.x) != 0) return (cmp_c(A.x, B.x) == -1);
return (cmp_c(A.y, B.y) == -1);
}
int search(double px, double py)
{
int l, r, c;
l = 1, r = N;
while (l <= r)
{
c = ((l + r) >> 1);
if (cmp_c(P[c].x, px) == 0 && cmp_c(P[c].y, py) == 0) return 1;
else
if (cmp_c(P[c].x, px) == -1 || (cmp_c(P[c].x, px) == 0 && cmp_c(P[c].y, py) == -1)) l = c+1;
else if (cmp_c(P[c].x, px) == +1 || (cmp_c(P[c].x, px) == 0 && cmp_c(P[c].y, py) == +1)) r = c-1;
}
return 0;
}
int exista(double x1, double y1, double x2, double y2)
{
/*x2 -= x1, y2 -= y1;
a = (x2-y2)/2.0, b = (x2+y2)/2.0;
punct.x = a + x1;
punct.y = b + y1;
ok1 = search(punct);
if (ok1)
{
punct.x = b + x1;
punct.y = y1 - a;
ok2 = search(punct);
if (ok2) return 1;
}*/
mx = (x1 + x2) / 2, my = (y1 + y2) / 2;
dx = fabs(mx - x1), dy = fabs(my - y1);
if (y1 < y2)
{
x3 = mx + dy, y3 = my - dx;
x4 = mx - dy, y4 = my + dx;
}
else
{
x3 = mx - dy, y3 = my - dx;
x4 = mx + dy, y4 = my + dx;
}
ok1 = search(x3, y3);
if (ok1)
{
ok2 = search(x4, y4);
if (ok2) return 1;
}
return 0;
}
int main()
{
freopen("patrate3.in", "r", stdin);
freopen("patrate3.out", "w", stdout);
scanf("%d", &N);
for (i = 1; i <= N; i++) scanf("%lf %lf", &P[i].x, &P[i].y);
sort(P+1, P+N+1, cmp);
Sol = 0;
for (i = 1; i <= N; i++)
for (j = i + 1; j <= N; j++)
if (exista(P[i].x, P[i].y, P[j].x, P[j].y)==1) Sol++;
printf("%d\n", Sol/2);
return 0;
}