//Deresu Roberto - FMI
//Re :)
#include<fstream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<map>
using namespace std;
int n,rez;
char sir[14];

struct punct
{
    long long x,y;
}a[1007];

map<long long,long long>mymap;
map<long long,long long> :: iterator it;

ifstream fin("patrate3.in");
ofstream fout("patrate3.out");

int cmp(punct a, punct b)
{
    if(a.x < b.x || (a.x == b.x && a.y < b.y)) return 1;
    return 0;
}

int cauta(long long x, long long y)
{
    it = mymap.find(x);

    while(it != mymap.end() && it->first == x)
    {
        if(it->second == y) return 1;
        it++;
    }

    return 0;
}

long long numar()
{
    int i;
    long long x, semn;
    i = 0;
    x = 0;
    semn = 1;

    fin>>sir;

    if(sir[0] == '-') semn = -1LL, i++;

    while(sir[i])
    {
        if(sir[i]!='.')
            x = x*10+1LL*(sir[i]-'0');
        i++;
    }

    return semn*x;
}

int main()
{
    fin>>n;

    for(int i=1;i<=n;i++)
    {
        a[i].x = numar();
        a[i].y = numar();
        mymap.insert(make_pair(a[i].x,a[i].y));
    }

    sort(a+1,a+n+1,cmp);

    for(int i=1;i<n;i++)
        for(int j=i+1;j<=n;j++)
        {
            long long x3,y3,x4,y4;

            x3 =a[i].x+a[i].y-a[j].y;
            y3 =a[i].y+a[j].x-a[i].x;
            x4 =a[j].x+a[i].y-a[j].y;
            y4 =a[j].y+a[j].x-a[i].x;

            if(cauta(x3,y3) && cauta(x4,y4)) rez++;
        }

    fout<<rez/2;

	return 0;
}