18000번 - One of Each 다국어

You are given a sequence of n integers X = [x₁, x₂, ..., x_n] and an integer k. It is guaranteed that 1 ≤ x_i ≤ k, and every integer from 1 to k appears in the list X at least once.

Find the lexicographically smallest subsequence of X that contains each integer from 1 to k exactly once.

The first line of input contains two integers n and k (1 ≤ k ≤ n ≤ 2 ∙ 10⁵), where n is the size of the sequence, and the sequence consists only of integers from 1 to k.

Each of the next n lines contains a single integer x_i (1 ≤ x_i ≤ k). These are the values of the sequence X in order. It is guaranteed that every value from 1 to k will appear at least once in the sequence X.

Output a sequence of integers on a single line, separated by spaces. This is the lexicographically smallest subsequence of X that contains every value from 1 to k.