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 CPP):

Solution:

#include <iostream>
#include <map>
#include <string>
#include <queue>
#include <string.h>
#include <math.h>
#define ll long long
using namespace std;

int main()
{
	std::ios::sync_with_stdio(false);
	int n;
	cin>>n;
	int maxe,mine,max_pos,min_pos;
	maxe = -10000005,max_pos = 1;
	mine = -maxe,min_pos = 1;
	int num[55];
	for(int i=1;i<=n;i++)
		cin>>num[i];
	for(int i=1;i<=n;i++)
	{
		if(maxe < num[i])
		{
			maxe = num[i];
			max_pos = i;
		}
		if(num[i] < mine)
		{
			mine = num[i];
			min_pos = i;
		}
	}
	cout<<n*2-2<<endl;
	if(abs(maxe) >= abs(mine))
	{
		for(int i=1;i<=n;i++)
		{
			if(i == max_pos);
			else
				cout<<max_pos<<" "<<i<<endl;
		}
		for(int i=2;i<=n;i++)
		{
			cout<<i-1<<" "<<i<<endl;
		}
	}
	else
	{
		for(int i=1;i<=n;i++)
		{
			if(i == min_pos);
			else cout<<min_pos<<" "<<i<<endl;
		}
		for(int i=n-1;i>=1;i--)
		{
			cout<<i+1<<" "<<i<<endl;
		}
	}
	return 0;
}