import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String args[]) throws IOException {
		// 2020/2/4 No.148
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int a = Integer.parseInt(br.readLine());
		int b = Integer.parseInt(br.readLine());
		int x = 1 ^ 2 ^ 3;
        x ^= a;
        x ^= b;

        System.out.println(x);

	}
}
/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