You are given an array of integers containing some duplicates as an argument. Return the first element in the array that is duplicated twice.

Requirements

• Must return an integer
• Must also handle negative integers
• Must be able to handle cases with multiple duplicate elements

Example #1

solve([6, 2, 5, 1, 0, 12, 2])
> 2

Example #2

solve([-6, 1, 5, -6, 0, -2, 3])
> -6

Example #3

solve([3, 1, 5, 1, 0, -2, 3, 5])
> 1

The number three appears twice, but both instances of the number one appear before both instances of three, so return one.