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>
using namespace std;
int main(){
    int N,ma=-1000001,mi=1000001,ma_idx=0,mi_idx=0;
    cin>>N;
    int a[N];
    for(int i=0;i<N;i++){
        cin>>a[i];
        if(ma<a[i])ma=a[i],ma_idx=i;
        if(mi>a[i])mi=a[i],mi_idx=i;
    }
    cout<<2*N-2<<endl;
    for(int i=0;i<N;i++){
        if(i==(abs(mi)<=abs(ma)?ma_idx:mi_idx))continue;
        cout<<(abs(mi)<=abs(ma)?ma_idx:mi_idx)+1<<" "<<i+1<<endl;
    }
    for(int i=1;i<N;i++)cout<<(abs(mi)<=abs(ma)?i:N-i+1)<<" "<<(abs(mi)<=abs(ma)?i+1:N-i)<<endl;
    return 0;
}