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<bits/stdc++.h>
using namespace std;
#define ll long long
int main()
{
	int n;
	cin>>n;
	int arr[n];
	vector<pair<int,int>>move;
	for(int i=0;i<n;i++)
		cin>>arr[i];
	//int c=0;
	int max=-1000006,min=1000006,maxind=0,minind=0;
	for(int i=0;i<n;i++)
	{
		if(max<arr[i])
		{
			max=arr[i];
			maxind=i;
		}
		if(min>arr[i])
		{
			min=arr[i];
			minind=i;
		}
	}
	cout<<2*n-1<<"\n";
	if(abs(max)<abs(min))
	{
		for(int i=0;i<n;i++)
			cout<<minind+1<<" "<<i+1<<"\n";
		for(int i=n-1;i>0;i--)
			cout<<i+1<<" "<<i<<"\n";
	}
	else
	{
		for(int i=0;i<n;i++)
			cout<<maxind+1<<" "<<i+1<<"\n";
		for(int i=0;i<n-1;i++)
			cout<<i+1<<" "<<i+2<<"\n";
	}
}