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<string>
#include<iomanip>
#include<math.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i = 1; i <= n; i++)
#define INF (long long)(1e18)
#define MOD (int)(1e9+7)
#define min(a,b) (a>b?b:a)
#define max(a,b) (a>b?a:b)
#define yn(f) (f?"Yes":"No")
#define YN(f) (f?"YES":"NO")
#define MAX 60

int a[MAX];
signed main(){
	cout<<fixed<<setprecision(7);
	bool flag = true;
	int n, m, ma = 0, A, ti = 0;
	string str;
	
	cin>>n;
	
	rep(i,n){
		cin>>A;
		if(ma <= abs(A)){
			ma = abs(A);
			ti = i;
			if(A >= 0) flag = true;
			else flag = false;
		}
	}
	
	cout<<n+n-1<<endl;
	for(int i = 1; i <= n; i++){
		cout<<ti<<" "<<i<<endl;
	}
	if(flag == true){
		for(int i = 2; i <= n; i++){
			cout<<i-1<<" "<<i<<endl;
		}
	} else {
		for(int i = n; i >= 2; i--){
			cout<<i<<" "<<i-1<<endl;
		}
	}
	return 0;
}