Problem: 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.

Examples

Input

3
-2 5 -1


Output

2
2 3
3 3


Input

2
-1 -3


Output

1
2 1


Input

5
0 0 0 0 0


Output

0

Solution (in JAVA):

Solution:
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int[] a = new int[n];
		int min = Integer.MAX_VALUE;
		int minIdx = 0;
		int max = Integer.MIN_VALUE;
		int maxIdx = 0;
		for(int i=0;i<n;i++) {
			int x = in.nextInt();
			a[i] = x;
			if(x<min) {
				min = x;
				minIdx = i;
			}
			if(x>max) {
				max = x;
				maxIdx = i;
			}
		}
		in.close();
		boolean plus = Math.abs(max) >= Math.abs(min);
		StringBuilder sb = new StringBuilder();
		String ls = System.lineSeparator();
		if(plus) {
			for(int i=0;i<n;i++) {
				if(i==maxIdx) continue;
				sb.append((maxIdx+1) + " " + (i+1) + ls);
			}
			for(int i=1;i<n;i++) {
				sb.append(i + " " + (i+1) + ls);
			}
		}else {
			for(int i=0;i<n;i++) {
				if(i==minIdx) continue;
				sb.append((minIdx+1) + " " + (i+1) + ls);
			}
			for(int i=n-1;i>=1;i--) {
				sb.append((i+1) + " " + i + ls);
			}
		}
		System.out.println(2*n-2);
		System.out.println(sb.toString());
		

	}

}