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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
class Program
{
    static void Main()
    {
        int first = int.Parse(ReadLine());
        string[] seconds = ReadLine().Split(' ');
        int[] second = new int[first];
        int min = 0;
        int max = 0;
        for (int i = 0; i < first; i++){
            second[i] = int.Parse(seconds[i]);
            if (second[i] > second[max])
                max = i;

            if (second[i] < second[min])
                min = i;
        }

        int plusNumber = second[max];
        int index = max;
        if (Math.Abs(second[max]) < Math.Abs(second[min]))
        {
            plusNumber = second[min];
            index = min;
        }

        System.Text.StringBuilder sb = new System.Text.StringBuilder();
        for (int i = 0; i < first; i++)
        {
            second[i] += plusNumber;
            sb.Append((index+1).ToString());
            sb.Append((' ').ToString());
            sb.Append((i+1).ToString());
            sb.Append('\n');
        }

        int processCount = first;
        for (int i = 0; i < first - 1; i++){
            second[i + 1] += second[i];
            sb.Append((i+1).ToString());
            sb.Append((' ').ToString());
            sb.Append((i+2).ToString());
            sb.Append('\n');
            processCount++;
        }
        WriteLine(processCount);
        WriteLine(sb.ToString());
    }
}