#include <cmath>
#define x first
#define y second
#include <fstream>
#include <vector>
#define eps 0.00000001

using namespace std;

ifstream fin ("patrate3.in");
ofstream fout ("patrate3.out");
const int Dim = 1001,mod = 636013;

typedef pair < double, double > Punct;

int n,cnt;
Punct A[Dim];
vector < Punct > H[mod];

bool Egal(Punct X, Punct Y)
{

    return fabs(X.x - Y.x) <= eps  and fabs(X.y - Y.y) <= eps;

}



bool Find(Punct X)
{
    int i = (int)X.x % mod;
    if ( i < 0)
        i += mod;
    for ( const auto & j : H[i])
        if ( Egal(j,X) )
            return 1;

    i = (int)(X.x+1) % mod;

    if ( i < 0)
        i += mod;

    for ( const auto & j : H[i])
        if ( Egal(j,X) )
            return 1;

    i = (int)(X.x-1) % mod;
    if ( i < 0)
        i += mod;
    for ( const auto & j : H[i])
        if ( Egal(j,X) )
            return 1;
    return 0;

}


void Insert(Punct X)

int i = (int)X.x % mod;

if ( i < 0)
    i += mod;

H[i].push_back(X);

}


int main()
{
    fin >> n;

    for ( int i = 1; i <= n; ++i)
    {

        fin >> A[i].x >> A[i].y;
        Insert(A[i]);
    }

    for ( int i = 1; i <= n; ++i)
        for ( int j = i + 1; j <= n; ++j)
        {
            Punct Mid,X,Y;
            Mid = {(A[i].x + A[j].x) / 2, (A[i].y + A[j].y) / 2};
            X = {Mid.x - (A[j].y - Mid.y), Mid.y + (A[j].x - Mid.x)};
            Y = {Mid.x + (A[j].y - Mid.y), Mid.y - (A[j].x - Mid.x)};
            if ( Find(X)and Find(Y))
                ++cnt;

        }

    fout << cnt/2;
}