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>
#define ll long long
#define foru(i,a,n) for(int i=(a); i<=(n); i++)
#define ford(i,n,a) for(int i=(n); i>=(a); i--)
using namespace std;
const int N = 111;
typedef pair<int,int> ii;
ll n, a[N], d[N], vt, amax;
vector <ii> cnt;
int main(){
    cin >>n;
    foru(i,1,n) cin >>a[i];
    vt = 1; amax = a[1];
    foru(i, 1, n) if(abs(a[i])>amax){
        vt = i;
        amax = abs(a[i]);
    }
    foru(i, 1, n) a[i] += a[vt];
    foru(i, 1, n) cnt.push_back(ii(vt,i));
    if(a[vt]>0){
        foru(i, 1, n-1) cnt.push_back(ii(i, i+1));
    }
    else{
        ford(i, n, 2) cnt.push_back(ii(i, i-1));
    }
    ///Print result
    cout <<cnt.size() <<"\n";
    for(int i=0; i<cnt.size(); ++i)
        cout <<cnt[i].first <<" " <<cnt[i].second <<"\n";
    return 0;
}