Score : $100$ points

问题陈述

高桥的蛋糕被人吃了。有三个嫌疑人：人 $1$，人 $2$，和人 $3$。

有两个证人，林果和斯努克。林果记得人 $A$ 不是罪犯，斯努克记得人 $B$ 不是罪犯。

根据两个证人的记忆，确定是否可以唯一确定罪犯。如果可以确定罪犯，请打印出这个人的编号。

以上为大语言模型 kimi 翻译，仅供参考。

Problem Statement

Takahashi's cake has been eaten by someone. There are three suspects: person $1$, person $2$, and person $3$.

There are two witnesses, Ringo and Snuke. Ringo remembers that person $A$ is not the culprit, and Snuke remembers that person $B$ is not the culprit.

Determine if the culprit can be uniquely identified based on the memories of the two witnesses. If the culprit can be identified, print the person's number.

Constraints

• $1 \leq A, B \leq 3$
• All input values are integers.

Input

The input is given from Standard Input in the following format:

$A$ $B$

Output

If the culprit can be uniquely identified based on the memories of the two witnesses, print the person's number; otherwise, print -1.

Sample Input 1

1 2

Sample Output 1

3

From the memories of the two witnesses, it can be determined that person $3$ is the culprit.

Sample Input 2

1 1

Sample Output 2

-1

From the memories of the two witnesses, it cannot be determined whether person $2$ or person $3$ is the culprit. Therefore, print -1.

Sample Input 3

3 1

Sample Output 3

2