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 Scala (2.11.7) (judge verdict: Wrong Answer)

object Main extends App {
	
	val N = scala.io.StdIn.readInt
	var A = scala.io.StdIn.readLine.split(" ").map(_.toInt)

	var i = 0

	var l1 = List[Int]()
	var l2 = List[Int]()

	do{
		if(A(i) > A(i+1)){
			if(A(i) < 0){
				A(i) = A(i) + A(i+1)
				l1 = (i+2) :: l1
				l2 = (i+1) :: l2
			}else{
				A(i+1) = A(i+1) + A(i)
				l1 = (i+1) :: l1
				l2 = (i+2) :: l2
			}
		}else{
			i = i + 1
		}

	}while(i < (N-1))

	if(l1.size == 0){
		println(0)
	}else{
		println(l1.size)

		l1 = l1.reverse
		l2 = l2.reverse

		for(i<-0 until l1.size){
			println(l1(i) + " " + l2(i))
		}
	}





}