package main

import "fmt"

func solve(n uint64) uint64 {
	ans := n
	if n%2 == 0 && n/2 > 2 {
		ans = n / 2
	}
	for i := uint64(3); i*i <= n; i++ {
		if n%i == 0 {
			ans = i
			break
		}
	}
	return ans
}

func main() {
	var n uint64
	fmt.Scan(&n)
	fmt.Println(solve(n))
}