Problem Statement

Let $N$ be a positive even number.

There is a permutation $p=(p_1, p_2, \dots, p_N)$ of $(1, 2, \dots N)$. Torao is trying to construct a permutation $q$ of $(1, 2, \dots, N)$ by the following procedure.

First, prepare an empty sequence $q$. Then repeat the following operation until $p$ becomes empty.

• Choose $2$ adjacent elements of $p$, and call them $x, y$. Remove $x, y$ from $p$ (at this point, $p$ becomes shorter by $2$), and append $x, y$ to the end of $q$, keeping them in this order.

When $p$ becomes empty, $q$ is a permutation of $(1,2,...,N)$.

Find the lexicographically smallest $q$.

Constraints

• $N$ is even.
• $2 \le N \le 2\times 10^5$
• $(p_1, p_2, \dots, p_N)$ is a permutation of $(1, 2, \dots, N)$.

Input

The input is given from standard input in the following format.

$N$
$p_1$ $p_2$ $\dots$ $p_N$

Output

Output the lexicographically smallest $q$, separated by spaces.

Sample

4
3 2 4 1

2 4 3 1

$p$                  $q$
$(3, 2, 4, 1)$          $()$
$(3, 1)$              $(2, 4)$ 
$()$                 $(2, 4, 3, 1)$ 

2
1 2

1 2

8
4 6 3 2 8 5 7 1

2 8 3 5 4 6 7 1