Problem Statement

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 $0$.

Constraints

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

Input

Input is given from Standard Input in the following format:

$a$ $b$ $c$

Output

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

Sample Input 1

2 5 2

Sample Output 1

5

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

Sample Input 2

4 5 6

Sample Output 2

0

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

Sample Input 3

1 1 1

Sample Output 3

1

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