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

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var a = NList;
        Array.Sort(a);
        var dp = new long[n + 1];
        dp[0] = 1;
        for (var i = 1; i < dp.Length; ++i) dp[i] = dp[i - 1] * i;
        var ans = dp[n];
        var tmp = 1;
        for (var i = 0; i < a.Length; ++i)
        {
            if (i + 1 == a.Length || a[i] != a[i + 1])
            {
                ans = ans / dp[tmp];
                tmp = 1;
            }
            else ++tmp;
        }
        WriteLine(ans);
    }
}