import java.util.*;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        boolean[] x = new boolean[3];
        int A = sc.nextInt();
        int B = sc.nextInt();
        x[A-1] = true;
        x[B-1] = true;
        int ans = 0;
        for (int i = 0; i < 3; i++) {
            if (!x[i]) {
                ans = i+1;
                break;
            }
        }

        System.out.println(ans);
    }
}

/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