package main

import (
	"bufio"
	"os"
	"strconv"
	"fmt"
)

func main() {
	X := nextInt()
	ans := 0
	if X < 9 {
		if X == 4 || X % 2 == 1 {
			fmt.Println(X)
		}else {
			fmt.Println(X / 2)
		}

	}else {

		for i := 3; i * i <= X; i++ {
			if X % i == 0 {
				ans = i
				break
			}
		}
		if ans > 0 {
			fmt.Println(ans)
		}else {
			fmt.Println(X)
		}
	}


}

var s = bufio.NewScanner(os.Stdin)

func next() string {
	s.Split(bufio.ScanWords)
	s.Scan()
	return s.Text()
}
func nextLine() string {
	s.Split(bufio.ScanLines)
	s.Scan()
	return s.Text()
}

func nextInt() int {
	i, e := strconv.Atoi(next())
	if e != nil {
		panic(e)
	}
	return i
}
func nextLong() int64 {
	i, e := strconv.ParseInt(next(), 10, 64)
	if e != nil {
		panic(e)
	}
	return i
}


func min(a int, b int) int {
	if a < b {
		return a
	}
	return b
}
func max(a int, b int) int {
	if a < b {
		return b
	}
	return a
}