Unique Elements Extraction

Given an array of integers, your task is to extract the unique elements and output them in the order they first appear. Do not use any built-in functions that directly perform this task.

More formally, if you are given an array \(A = [a_1, a_2, \dots, a_n]\), you need to produce another array \(B\) such that each element in \(B\) is unique and appears in the same order as in \(A\), i.e., \(B = [b_1, b_2, \dots, b_k]\) where each \(b_i\) is the first occurrence of that particular value in \(A\).

Example:

Input: 8
       4 5 9 4 5 6 7 9
Output: 4 5 9 6 7

inputFormat

The first line of input contains an integer \(n\), representing the number of elements in the array. The second line contains \(n\) space-separated integers.

outputFormat

Output the unique elements of the array in a single line, separated by a space, in the order they appeared in the input.

8
4 5 9 4 5 6 7 9

4 5 9 6 7