#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <vector>
using namespace std ;
#define eqs 1e-9
struct node{
    double x , y ;
}p[1100] ;
bool cmp(node a,node b)
{
    return ( a.x < b.x || ( a.x == b.x && a.y < b.y ) ) ;
}
bool judge(double x,double y,int n)
{
    int low = 0 , mid , high = n-1 ;
    while( low <= high )
    {
        mid = (low + high) / 2 ;
        if( fabs(p[mid].x-x) < eqs && fabs(p[mid].y-y) < eqs )
            return true ;
        else if( p[mid].x-x > eqs || ( fabs(p[mid].x-x) < eqs && p[mid].y-y > eqs ) )
            high = mid - 1 ;
        else
            low = mid + 1 ;
    }
    return false ;
}
int main()
{
    int n , i , j , num ;
    double x , y , xx , yy ;
    while( scanf("%d", &n) !=EOF)
    {
        num = 0 ;
        for(i = 0 ; i < n ; i++)
        {
            scanf("%lf %lf", &p[i].x, &p[i].y) ;
        }
        sort(p,p+n,cmp) ;
        for(i = 0 ; i < n ; i++)
        {
            for(j = i+1 ; j < n ; j++)
            {
                if( i == j ) continue ;
                x = (p[i].x+p[j].x)/2 ;
                y = (p[i].y+p[j].y)/2 ;
                xx = p[i].x - x ;
                yy = p[i].y - y ;
                if( judge(x+yy,y-xx,n) && judge(x-yy,y+xx,n) )
                {
                    num++ ;
                }
            }
        }
        printf("%d\n", num/2) ;
    }
    return 0;
}
 

#include <bits/stdc++.h>  
#define ll long long
#define mk make_pair
#define y1 yyy
using namespace std;
const int N = 1e3 + 5;
map< pair<int, int>, bool> M;  
int x[N], y[N], n, ans;
int main() {
	int T;
	while (scanf("%d", &n) != EOF) {
		ans = 0;
		M.clear();
		for (int i = 1; i <= n; i++) {
			scanf("%d %d", x + i, y + i);
			M[mk(x[i], y[i])] = 1;
			
		}
		for (int i = 1; i <= n; i++) {
			for (int j = i + 1; j <= n; j++) {
				int dx = y[j] - y[i];
				int dy = x[i] - x[j];
				int ok = 0; 
				if (M.count(mk(x[i] + dx, y[i] + dy))) ok++;
				if (M.count(mk(x[j] + dx, y[j] + dy))) ok++;
				if (ok == 2) ans++;
				ok = 0;
				if (M.count(mk(x[i] - dx, y[i] - dy))) ok++;
				if (M.count(mk(x[j] - dx, y[j] - dy))) ok++;
				if (ok == 2) ans++;
			}
		}
		printf("%d\n", ans / 4);
	}
}