#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;
}