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 a = long.Parse(ReadLine());
        var ans = int.MaxValue;
        for (var n = 2; n < 62; ++n)
        {
            var all = (long)n;
            var prev = 1L;
            for (var m = 1; m < 62; ++m)
            {
                if (all >= a)
                {
                    ans = Math.Min(ans, n * m);
                    break;
                }
                prev = all;
                all = all * n;
                if (all < prev || all / n != prev)
                {
                    ans = Math.Min(ans, n * m);
                    break;
                }
            }
        }
        WriteLine(ans);
    }
}