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.*;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		long a[] = new long[N];
		for(int i=0;i<N;i++)a[i]=sc.nextInt();
		sc.close();
		
		long max = Long.MIN_VALUE/2;
		long min = Long.MAX_VALUE/2;
		
		long maxP = 0;
		long minP = 0;
		
		for(int i=0;i<N;i++) {
			if(max < a[i]) {
				max = a[i];
				maxP = i;
 			}
			if(min > a[i]) {
				min = a[i];
				minP = i;
			}
		}
		StringBuilder sb = new StringBuilder();
		int cnt = 2*(N-1); //fixed
		sb.append(cnt + "\n");
		if(max + min >= 0) {
			sb.append((maxP+1) + " " + (2) + "\n"); 
			sb.append((maxP+1) + " " + (2) + "\n"); 
			for(int i=2;i<N;i++) {
				sb.append((i) + " " + (i+1) + "\n"); 
				sb.append((i) + " " + (i+1) + "\n"); 
			}
		}
		else {
			sb.append((minP+1) + " " + (N-1) + "\n"); 
			sb.append((minP+1) + " " + (N-1) + "\n");
			for(int i=N-2;i>=1;i--) {
				sb.append((i+1) + " " + (i) + "\n"); 
				sb.append((i+1) + " " + (i) + "\n"); 
			}
		}
		System.out.println(sb.toString());
	}
	
}