import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args)  {
        Set<Integer> set = new HashSet<>();
        set.add(1);
        set.add(2);
        set.add(3);
        String line;
        try(BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
            while((line = br.readLine()) != null) {
                int num = Integer.parseInt(line);
                set.remove(num);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println(set.iterator().next());
    }
}
/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