Problem:
Score : 600 points

Problem Statement

Snuke has an integer sequence, a, of length N. The i-th element of a (1-indexed) is a_{i}.

He can perform the following operation any number of times:

Operation: Choose integers x and y between 1 and N (inclusive), and add a_x to a_y.

He would like to perform this operation between 0 and 2N times (inclusive) so that a satisfies the condition below. Show one such sequence of operations.
It can be proved that such a sequence of operations always exists under the constraints in this problem.

Condition: a_1 \leq a_2 \leq ... \leq a_{N}

Constraints

2 \leq N \leq 50

-10^{6} \leq a_i \leq 10^{6}

All input values are integers.

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_{N}

Output

Let m be the number of operations in your solution. In the first line, print m.
In the i-th of the subsequent m lines, print the numbers x and y chosen in the i-th operation, with a space in between.
The output will be considered correct if m is between 0 and 2N (inclusive) and a satisfies the condition after the m operations.

Sample Input 1

3
-2 5 -1

Sample Output 1

2
2 3
3 3

After the first operation, a = (-2,5,4).

After the second operation, a = (-2,5,8), and the condition is now satisfied.

Sample Input 2

2
-1 -3

Sample Output 2

1
2 1

After the first operation, a = (-4,-3) and the condition is now satisfied.

Sample Input 3

5
0 0 0 0 0

Sample Output 3

0

The condition is satisfied already in the beginning.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.Scanner;

public class Main{

    public static void main(String[] args) {
        
        Scanner scan = new Scanner(System.in);

        int n = scan.nextInt();
        int[] array = new int[n];
        for(int i=0; i<n; i++){
            array[i] = scan.nextInt();
        }
        ArrayList<String> list = new ArrayList<>();
        for(int i=1; i<n; i++){
            
            while(true){
                if(array[i-1] < 0 && array[i-1] > array[i]){
                    array[i-1] += array[i];
                    list.add((i+1) + " " + i);
                }else if(array[i-1] > array[i]){
                    array[i] += array[i-1];
                    list.add(i + " " + (i+1));
                }else{
                    break;
                }
            }
        }
        
        scan.close();
        System.out.println(list.size());
        for(String s : list){
            System.out.println(s);
        }
    }
}