using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;

class Magatro
{
    static void Main()
    {
        long N = long.Parse(Console.ReadLine());
        for(int i = 3; i <= Math.Sqrt(N); i++)
        {
            if (N % i == 0)
            {
                Console.WriteLine(i);
                return;
            }
        }
        Console.WriteLine(N);
    }

}