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;

void Main() {
  int N;
  cin >> N;
  long long a[N];
  long long max_v = 0, min_v = 1e9;
  int max_idx = 0, min_idx = 0;
  for (int i = 0; i < N; i++) {
    cin >> a[i];
    if (a[i] > max_v) {
      max_v = a[i];
      max_idx = i;
    }
    if (a[i] < min_v) {
      min_v = a[i];
      min_idx = i;
    }
  }
  cout << N + N - 1 << endl;
  if (abs(max_v) >= abs(min_v)) {
    for (int i = 1; i <= N; i++) {
      cout << max_idx + 1 << " " << i << endl;
    }
    for (int i = 1; i < N; i++) {
      cout << i << " " << i + 1 << endl;
    }
  } else {
    for (int i = 1; i <= N; i++) {
      cout << min_idx + 1 << " " << i << endl;
    }
    for (int i = N; i > 1; i--) {
      cout << i << " " << i - 1 << endl;
    }
  }
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  std::cout << std::fixed << std::setprecision(15);
  Main();
  return 0;
}