Maximum Number of Packages
In Amazon's online marketplace, the inventory manager is exploring strategies to enhance product sales. The focus is on creating appealing packages that offer customers a delightful shopping experience. To achieve this, the inventory manager aims to construct packages, each containing at most 2 items, to have an equal total cost across all packages. The total cost of a package is defined as the sum of the costs of the items contained within.
Task: Given an array cost of size n, representing the costs of individual items, determine the maximum number of packages that can be created, such that each package adheres to the constraint of having at most 2 items, and all packages have the same cost.
Note: Each item can be used in at most one package.
Constraints
1 ≤ n ≤ 2 x 105
1 ≤ cost[i] ≤ 2000
1Example 1

Constraints
Limits and guarantees your solution can rely on.
n ≤ 2 x 1051 ≤
cost[i] ≤ 2000