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 JAVA):

Solution:

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class Main {
    public static void main(final String[] args) {
        final Scanner scanner = new Scanner(System.in);
        final int n = scanner.nextInt();
        final long[] array = new long[n + 1];
        int max = -1_000_001;
        int maxIndex = -1;
        int min = 1_000_001;
        int minIndex = -1;
        for (int i = 1; i <= n; i++) {
            final int a = scanner.nextInt();
            array[i] = a;
            if (a > max) {
                max = a;
                maxIndex = i;
            }
            if (a < min) {
                min = a;
                minIndex = i;
            }
        }

        int count;
        final List<Pair> operations;
        if (max == min) {
            System.out.println(0);
            return;
        }

        if (min >= 0) {
            count = 0;
            operations = new ArrayList<>();
            for (int i = 1; i < n; i++) {
                if (array[i] > array[i + 1]) {
                    array[i + 1] += array[i];
                    count++;
                    operations.add(new Pair(i, i + 1));
                }
            }

            System.out.println(count);
            operations.stream()
                    .map(Pair::toString)
                    .forEach(System.out::println);
            return;
        }

        if (max <= 0) {
            operations = new ArrayList<>();
            count = 0;
            for (int i = n - 1; i >= 1; i--) {
                if (array[i] > array[i + 1]) {
                    array[i] += array[i + 1];
                    count++;
                    operations.add(new Pair(i + 1, i));
                }
            }

            System.out.println(count);
            operations.stream()
                    .map(Pair::toString)
                    .forEach(System.out::println);
            return;
        }

        count = n;
        if (max >= -min) {
            for (int i = 1; i <= n; i++) {
                array[i] += max;
            }
            int finalized = maxIndex;
            operations = IntStream.rangeClosed(1, n)
                    .mapToObj(i -> new Pair(finalized, i))
                    .collect(Collectors.toList());
            for (int i = 1; i < n; i++) {
                if (array[i] > array[i + 1]) {
                    array[i + 1] += array[i];
                    count++;
                    operations.add(new Pair(i, i + 1));
                }
            }
        } else {
            for (int i = 1; i <= n; i++) {
                array[i] += min;
            }
            int finalized = minIndex;
            operations = IntStream.rangeClosed(1, n)
                    .mapToObj(i -> new Pair(finalized, i))
                    .collect(Collectors.toList());
            for (int i = n - 1; i >= 1; i--) {
                if (array[i] > array[i + 1]) {
                    array[i] += array[i + 1];
                    count++;
                    operations.add(new Pair(i + 1, i));
                }
            }
        }

        System.out.println(count);
        operations.stream()
                .map(Pair::toString)
                .forEach(System.out::println);
    }

    private static class Pair {
        final int addFrom;
        final int addTo;

        Pair(final int addFrom, final int addTo) {
            this.addFrom = addFrom;
            this.addTo = addTo;
        }

        @Override
        public String toString() {
            return addFrom + " " + addTo;
        }
    }
}