Maximize capacity with primary-backup pairing

You are given `n` servers, where server `i` has memory capacity `memory[i]`. A valid system must contain an **even** number of servers. If the system contains `2x` servers, then: - exactly `x` servers are designated as **primary** - exactly `x` servers are designated as **backup** - every primary server `P` must be paired with a **distinct** backup server `B` such that `memory[B] >= memory[P]` The **system memory capacity** is defined as the **sum of memory capacities of all primary servers**. Task: Given `n` and the array `memory`, compute the **maximum possible** system memory capacity over all valid choices of an even-sized subset of servers and a valid primary/backup pairing. Complete the function: - `maximumCapacity(memory)` → returns a 64-bit integer (long) Constraints: - `2 <= n <= 2 * 10^5` - `memory[i]` are integers (assume non-negative) Notes: - You may choose any even number of servers from the `n` servers (you do not have to use all servers). - Each server can be used at most once (either primary or backup, or not chosen).