Given an array of ages, determine the total number of friend requests made based on age conditions.
Example 1:
Input: ages = [16, 16]
Output: 2
Explanation: Both people send requests to each other.
Example 2:
Input: ages = [16, 17, 18]
Output: 2
Explanation: Friend requests are made 17->16 and 18->17.
Example 3:
Input: ages = [20, 30, 100, 110, 120]
Output: 3