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 <vector>

using namespace std;

int main() {
    int n;
    cin >> n;
    int ma = 0, mi = 0;
    vector<int> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        if (a[i] > a[ma])ma = i;
        if (a[i] < a[mi])mi = i;
    }

    vector<vector<int>> ope;
    if (a[ma] * 2 + a[0] > -(a[mi] * 2 + a[n - 1])) {
        ope.push_back({ma, 0});
        for (int i = 1; i < n; i++) ope.push_back({i - 1, i});
    } else {
        ope.push_back({mi, n - 1});
        for (int i = n - 1; i > 0; i--) ope.push_back({i, i - 1});
    }

    cout << ope.size() * 2 << endl;
    for (auto x:ope) {
        cout << x[0] + 1 << " " << x[1] + 1 << endl;
        cout << x[0] + 1 << " " << x[1] + 1 << endl;
    }
    return 0;
}