Problem Statement
You are given a sequence A=(A_1,A_2,\ldots,A_N)A=(A1,A2,…,AN) of length NN consisting of non-negative integers.
Determine if there is an even number represented as the sum of two different elements of AA. If it exists, find the maximum such number.
Constraints
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2\leq N \leq 2\times 10^52≤N≤2×105
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0\leq A_i\leq 10^90≤Ai≤109
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The elements of AA are distinct.
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All values in the input are integers.
Input
The input is given from Standard Input in the following format:
NNA_1A1A_2A2\ldots…A_NAN
Output
Print -1 if there is no even number represented as the sum of two different elements of AA.
If such an even number exists, print the maximum such number.