import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long x = 1;
        while (n > x) {
            if ((n & x) != 0) {
                n ^= x;
            }
            x <<= 1;
        }
        System.out.println(n);
    }
}