Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

The problem statement has recently been changed. View the changes.

×
A. Cards

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputThere are *n* cards (*n* is even) in the deck. Each card has a positive integer written on it. *n* / 2 people will play new card game. At the beginning of the game each player gets two cards, each card is given to exactly one player.

Find the way to distribute cards such that the sum of values written of the cards will be equal for each player. It is guaranteed that it is always possible.

Input

The first line of the input contains integer *n* (2 ≤ *n* ≤ 100) — the number of cards in the deck. It is guaranteed that *n* is even.

The second line contains the sequence of *n* positive integers *a*_{1}, *a*_{2}, ..., *a*_{n} (1 ≤ *a*_{i} ≤ 100), where *a*_{i} is equal to the number written on the *i*-th card.

Output

Print *n* / 2 pairs of integers, the *i*-th pair denote the cards that should be given to the *i*-th player. Each card should be given to exactly one player. Cards are numbered in the order they appear in the input.

It is guaranteed that solution exists. If there are several correct answers, you are allowed to print any of them.

Examples

Input

6

1 5 7 4 4 3

Output

1 3

6 2

4 5

Input

4

10 10 10 10

Output

1 2

3 4

Note

In the first sample, cards are distributed in such a way that each player has the sum of numbers written on his cards equal to 8.

In the second sample, all values *a*_{i} are equal. Thus, any distribution is acceptable.

Codeforces (c) Copyright 2010-2021 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Mar/05/2021 11:12:50 (h1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|