Takahashi threw three dice, and they showed three numbers $a$, $b$, and $c$.

If there are two same numbers among $a$, $b$, and $c$, print the remaining number. Otherwise, print $0$.

Input is given from Standard Input in the following format:

```
$a$ $b$ $c$
```

If there are two same numbers among $a$, $b$, and $c$, print the remaining number. Otherwise, print $0$.

-   $1 \leq a,b,c \leq 6$
-   All of $a$, $b$, and $c$ are integers.

5

The first and third dice both showed 2, so we should print the number on the remaining dice, which is 5.

0

Any two numbers are different, so we should print 0.

1

Any two numbers are the same. Whichever two dice we choose, the number on the remaining dice will be 1.