package main

import "fmt"

func main() {
	var n int
	_, _ = fmt.Scan(&n)

	p := make([]int, 0) // 試行した数字をためる
	for i := 3; i <= n; i++ {
		contain := false
		for _, num := range p {
			if i%num == 0 {
				contain = true
				break
			}
		}
		if contain {
			continue
		}

		if n%i == 0 {
			fmt.Println(i)
			return
		}

		p = append(p, i)
	}

	fmt.Println(n)
}