Given an array of integers, determine if any element is an outlier. An outlier is a number that is neither in the original array nor the sum of the other elements in the array. Find the largest outlier if one exists.

Input:

arr: An integer array.

Output:

The largest outlier in the array, or $-1$ if no outlier exists.

Example:

arr: $[4,1,3,16,2,10]$

Output: $16$

Task:

Write a function that takes the arr array as input and returns the largest outlier, or $-1$ if no outlier exists.