import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		List<Integer> in = new ArrayList<>();
		Integer a = sc.nextInt();
		Integer b = sc.nextInt();
		sc.close();
		in.add(1);in.add(2);in.add(3);
		if(in.contains(a)) in.remove(a);
		if(in.contains(b)) in.remove(b);
		System.out.println(in.get(0));
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz