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

 
public class Main {
 
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		String b = sc.next();
		
		ArrayList<String> candidate = new ArrayList<>();
		candidate.add("1");
		candidate.add("2");
		candidate.add("3");
		
		candidate.remove(a);
		candidate.remove(b);
		
		System.out.println(candidate.get(0));
		sc.close();

	}
}
	
/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