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.

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.

Constraints

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

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.

见题面 Input 部分

见题面 Output 部分