#include <bits/stdc++.h>

using namespace std;

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

double err = 0.00001;

int cnt = 0;

unordered_map <int, vector< pair<double, double> > > H;

int HashF( double x, double y ) {
    return x;
}

bool Check_points( double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4 ) {
    return ( abs( x1 + x2 - x3 - x4 ) < err && abs( y1 + y2 - y3 - y4 ) < err );
}

void Check( double x1, double y1, double x2, double y2 ) {
    double x3, y3, x4, y4;
    double C;

    C = x1 + x2 - abs( y1 - y2 );

    x3 = C / 2;
    x4 = x3 + abs( y1 - y2 );

    C = y1 + y2 - abs( x1 - x2 );

    y3 = C / 2;
    y4 = y3 + abs( x1 - x2 );

    if( !Check_points( x1, y1, x2, y2, x3, y3, x4, y4 ) )
        swap( y3, y4 );

    //fout << x1 << ' ' << y1 << ' ' << x2 << ' ' << y2 << '\n';
    //fout << x3 << ' ' << y3 << ' ' << x4 << ' ' << y4 << '\n';

    int hf = HashF( x3, y3 );

    for( int i = 0; i < H[hf].size(); ++i )
        if( abs( H[hf][i].first - x3 ) < err && abs( H[hf][i].second - y3 ) < err ) {
            //fout << H[hf][i].first << ' ' << H[hf][i].second << '\n';

            ++cnt;
            break;
        }

    hf = HashF( x4, y4 );

    for( int i = 0; i < H[hf].size(); ++i )
        if( abs( H[hf][i].first - x4 ) < err && abs( H[hf][i].second - y4 ) < err ) {
            ++cnt;
            break;
        }
}

int main()
{
    int N;
    vector <pair<double, double> > V;

    fin >> N;

    for( int i = 1; i <= N; ++i ) {
        double x, y;

        fin >> x >> y;

        x += 10001;
        y += 10001;

        V.push_back( { x, y } );
        H[x].push_back( { x, y } );
    }

    for( int i = 0; i < V.size(); ++i )
        for( int j = i + 1; j < V.size(); ++j )
            Check( V[i].first, V[i].second, V[j].first, V[j].second );

    //Check( V[0].first, V[0].second, V[8].first, V[8].second );

    fout << cnt / 2 << '\n';

    return 0;
}