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EIUPH007 - The largest even number

Given a positive integer N. Find the largest even digits in N.

Input

A single line consists of positive integers N (N <= 10 ^ 18).

Output

A single integer is the result. If there are no even digits, output -1.

Example

Input:
68

Output:
8

Added by:Ha Minh Ngoc
Date:2015-01-28
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:CSHARP C++ 4.3.2 CPP CPP14 JAVA
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