using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var map = NArr(n);
        var dic = new Dictionary<long, Dictionary<Fraction, long>>();
        var w = 2_000_000_001L;
        for (var i = 0; i < n; ++i) for (var j = i + 1; j < n; ++j)
        {
            var cx = map[i][0] + map[j][0];
            var cy = map[i][1] + map[j][1];
            var key = cx * w + cy;
            if (!dic.ContainsKey(key)) dic.Add(key, new Dictionary<Fraction, long>());
            var f = new Fraction(map[j][1] - map[i][1], map[j][0] - map[i][0]);
            if (dic[key].ContainsKey(f)) ++dic[key][f];
            else dic[key][f] = 1;
        }
        var ans = 0L;
        foreach (var kv in dic)
        {
            foreach (var fkv in kv.Value)
            {
                if (fkv.Key.Ch <= 0 && fkv.Key.Pa != 0) continue;
                var rev = new Fraction(- fkv.Key.Pa, fkv.Key.Ch);
                if (kv.Value.ContainsKey(rev)) ans += fkv.Value * kv.Value[rev];
            }
        }
        WriteLine(ans);
    }
class Fraction : IComparable<Fraction>
{
    public static Fraction ERR = new Fraction(1, 0);
    public static Fraction BASE = new Fraction(0, 1);
    public long Ch;
    public long Pa;
    public Fraction(long ch)
    {
        Ch = ch; Pa = 1;
    }
    public Fraction(long ch, long pa)
    {
        var gcd = GCD(ch, pa);
        if (pa < 0) gcd = -gcd;
        Ch = ch / gcd;
        Pa = pa / gcd;
    }
    public Fraction Mul(Fraction b)
    {
        var g1 = GCD(Pa, b.Ch);
        var g2 = GCD(Ch, b.Pa);
        return new Fraction(Ch / g2 * b.Ch, Pa / g1 * b.Pa);
    }
    public Fraction Mul(long b)
    {
        return Mul(new Fraction(b, 1));
    }
    public Fraction Div(Fraction b)
    {
        return Mul(b.Inv());
    }
    public Fraction Inv()
    {
        return new Fraction(Pa, Ch);
    }
    public Fraction Add(Fraction b)
    {
        var gcd = GCD(Pa, b.Pa);
        var nc = Ch * (b.Pa / gcd) + b.Ch * (Pa / gcd);
        var np = Pa / gcd * b.Pa;
        return new Fraction(nc, np);
    }
    public Fraction Add(long b)
    {
        return Add(new Fraction(b, 1));
    }
    public Fraction Sub(Fraction b)
    {
        return Add(b.Rev());
    }
    public Fraction Rev()
    {
        return new Fraction(-Ch, Pa);
    }
    long GCD(long a, long b)
    {
        a = Math.Abs(a);
        b = Math.Abs(b);
        if (a < b) return GCD(b, a);
        if (b == 0) return a;
        if (a % b == 0) return b;
        return GCD(b, a % b);
    }
    public int CompareTo(Fraction b)
    { checked {
        var left = Ch * b.Pa;
        var right = Pa * b.Ch;
        return left.CompareTo(right);
    } }
    public override bool Equals(object obj)
    {
        var b = (Fraction)obj;
        return Ch == b.Ch && Pa == b.Pa;
    }
    public override int GetHashCode()
    {
        return (int)(Ch * 1_000_000_000L % 1_000_000_007 * Pa % 1_000_000_007);
    }
    public override string ToString()
    {
        return $"{Ch}/{Pa}";
    }

    /// <summary>2点を通る直線 y = ax + b を返す</summary>
    public static (Fraction a, Fraction b) Line(long ax, long ay, long bx, long by)
    {
        if (ax == bx) return (Fraction.ERR, new Fraction(- ax));
        var s = new Fraction(by - ay, bx - ax);
        return (s, new Fraction(ay).Add(s.Mul(new Fraction(ax)).Rev()));
    }
    /// <summary>2直線の交点を求める 存在しないor無限に存在する場合false</summary>
    public static (bool result, Fraction x, Fraction y) Cross(Fraction a1, Fraction b1, Fraction a2, Fraction b2)
    {
        if (a1.Equals(a2)) return (false, Fraction.BASE, Fraction.BASE);
        if (a1.Equals(Fraction.ERR)) return (true, b1.Rev(), b2);
        if (a2.Equals(Fraction.ERR)) return (true, b2.Rev(), b1);
        var x = b2.Sub(b1).Div(a1.Sub(a2));
        return (true, x, a1.Mul(x).Add(b1));
    }
    public static Fraction Length2(long ax, long ay, long bx, long by)
    {
        return Length2(new Fraction(ax), new Fraction(ay), new Fraction(bx), new Fraction(by));
    }
    public static Fraction Length2(long ax, long ay, Fraction bx, Fraction by)
    {
        return Length2(new Fraction(ax), new Fraction(ay), bx, by);
    }
    public static Fraction Length2(Fraction ax, Fraction ay, Fraction bx, Fraction by)
    {
        var x = ax.Sub(bx);
        var y = ay.Sub(by);
        return x.Mul(x).Add(y.Mul(y));
    }
}
}