#include<fstream>
#include<cstring>
#include<vector>
#include<algorithm>
#include<cstring>
using namespace std;

vector<pair<long double,long double> >v;
int n,i,j,k,sol;
long double x[1005],y[1005];

ifstream f("patrate3.in");
ofstream g("patrate3.out");

int main()
{
    f>>n;
    for(i=1;i<=n;i++)
    {
        f>>x[i]>>y[i];
        x[i]*=1000000;
        y[i]*=1000000;
        v.push_back(make_pair(x[i],y[i]));
    }
    sort(v.begin(),v.end());
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
        {
           pair<long double,long double>px,py;
           px.first=x[i]+y[i]-y[j];
           px.second=x[j]+y[i]-x[i];
           py.first=x[j]+y[i]-y[j];
           py.second=x[j]+y[j]-x[i];
           if (binary_search(v.begin(),v.end(),px) && binary_search(v.begin(),v.end(),py))
                sol++;
        }
    g<<sol/2<<"\n";
}