The largest average#1477
On the board, there are integers, each labeled from to . You can select any two numbers, erase them, and replace them with a new number that is their arithmetic mean. This new number is assigned the label n + 1. You repeat this process: choose two numbers, compute their mean, and replace them with a new number labeled n + 2, and so on. This continues until only one number remains on the board. The goal is to maximize the value of this final number.
Your task is to determine the sequence of actions that will result in the largest possible final number.
The first line contains an integer (1 \leq n \leq 10^5). The second line contains integers initially written on the board. Each number is within the range from to .
Output n - 1 lines, each containing two integers separated by a space. These integers represent the labels of the numbers chosen at each step.
Example 1