Problem Statement

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.

Constraints

• $2\\leq N \\leq 2\\times 10^5$
• $0\\leq A_i\\leq 10^9$
• The elements of $A$ are distinct.
• All values in the input are integers.

Input

The input is given from Standard Input in the following format:

$N$ $A_1$ $A_2$ $\\ldots$ $A_N$

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.

Sample Input 1

3
2 3 4

Sample Output 1

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 Input 2

2
1 0

Sample Output 2

-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.