import java.util.*;
import java.lang.*;
import java.io.*;

class Ideone
{

	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner scan = new Scanner(System.in);
		long a = scan.nextLong();
		long b = scan.nextLong();
		
		long res = 0;
		for (int bit = 32; bit >= 0; --bit) {
			long bita = a & (1L << bit);
			long bitb = b & (1L << bit);
			if (bita != bitb) break;
			res |= bita;
		}
		System.out.println(res);
	}	
}