package main

import . "fmt"

func main() {
	var n int64
	Scan(&n)
	a:=[]int64{}
	for c:=int64(1); c <= n; c = c*2 {
		if (n&c)==c {
			a=append(a, c)
		}
	}
	h:=(int64(1)<<len(a))/2
	var ans int64
	for c:=int64(1); c <=h && len(a)> 0; c = c*2 {
		if (h&c) == c {
			ans |= a[0]
		}
		a=a[1:]
	}
	Println(ans)
}