You are given three integers, A, B and C.
Among them, two are the same, but the remaining one is different from the rest.
For example, when A=5,B=7,C=5, A and C are the same, but B is different.
Find the one that is different from the rest among the given three integers.

Constraints

• -$100 \leq A,B,C \leq 100$
• A, B and C are integers.
• The input satisfies the condition in the statement.

Input

Input is given from Standard Input in the following format:

A B C

Output

Among A, B and C, print the integer that is different from the rest.

Examples

Input

5 7 5

Output

7

Input

1 1 7

Output

7

Input

-100 100 100

Output

-100

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