To solve math problem


A student needs to solve a math problem. In this problem, he has given a set of numbers, and he has to figure out the maximum sum of the subset.
There is one necessity to do this that he should make subsets of non-siblings numbers. For example, if there is (2, 3, 4, 5, 6), so he needs to make subsets like (2,4,6), (2,4), (3,5), (3,6), (4, 6).

Write a function solve that should accept ONE parameter and return the maximum sum of the subset.

Function should accept the following parameter(s):
1.) a = an array of integers

Example
Input:
There is a set of numbers:
a = [2, -5, 6, 77, -3]
Output:
The function will return,
79

Explanation
It's subsets will be:
[2, 6, 3], [2, 6], [2, 77], [2, -3], [-5, 77], [-5, -3], [6, -3]
The maximum sum subset will be [2, 77].

Constraints
• The length on a set will be greater than 1 and less than 1000.
• Numbers in sets will be greater than -10000 and less than 10000.