7172: ABC272 —— C - Max Even
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Description
You are given a sequence $A=(A_1,A_2,\ldots,A_N)$ of length $N$ consisting of non-negative integers.
Determine if there is an even number represented as the sum of two different elements of $A$. If it exists, find the maximum such number.
Determine if there is an even number represented as the sum of two different elements of $A$. If it exists, find the maximum such number.
Input
The input is given from Standard Input in the following format:
$N$
$A_1\ A_2\ \ldots\ A_N$
$N$
$A_1\ A_2\ \ldots\ A_N$
Output
Print -1 if there is no even number represented as the sum of two different elements of $A$.
If such an even number exists, print the maximum such number.
If such an even number exists, print the maximum such number.
Constraints
$2≤N≤2×10^5$
$0\leq A_i\leq 10^9$
The elements of $A$ are distinct.
All values in the input are integers.
$0\leq A_i\leq 10^9$
The elements of $A$ are distinct.
All values in the input are integers.
Sample 1 Input
3
2 3 4
Sample 1 Output
6
The values represented as the sum of two distinct elements of A are 5, 6, and 7. We have an even number here, and the maximum is 6.
Sample 2 Input
2
1 0
Sample 2 Output
-1
The value represented as the sum of two distinct elements of A is 1. We have no even number here, so -1 should be printed.