/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
        Scanner scan = new Scanner(System.in);
		int b = Integer.parseInt(scan.nextLine());
 
        int firstZeroBit = ~b & (b + 1);
        if(firstZeroBit == 1) {
            int firstOneBit = b & ~(b - 1);
            System.out.println(b - (firstOneBit >>> 1));
        } else {
            System.out.println(b + (firstZeroBit >>> 1));
        }
	}
}

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Mjc=

27