Problem:
Score : 600 points

Problem Statement

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.

Sample Input 1

3
-2 5 -1

Sample Output 1

2
2 3
3 3

After the first operation, a = (-2,5,4).

After the second operation, a = (-2,5,8), and the condition is now satisfied.

Sample Input 2

2
-1 -3

Sample Output 2

1
2 1

After the first operation, a = (-4,-3) and the condition is now satisfied.

Sample Input 3

5
0 0 0 0 0

Sample Output 3

0

The condition is satisfied already in the beginning.

Solution in Python (3.4.3) (judge verdict: Wrong Answer)

def solve():
    n = int(input())
    A = list(map(int, input().split()))

    def check(B):
        #print(B)
        for i in range(n - 1):
            if B[i] > B[i + 1]:
                return False
        return True

    def out(ans):
        print(len(ans))
        for a in ans:
            print(a[0] + 1, a[1] + 1)

    mai = -1
    mii = -1
    ma = -10 ** 30
    mi = 10 ** 30

    for i in range(n):
        if A[i] > ma:
            ma = A[i]
            mai = i
        if A[i] < mi:
            mi = A[i]
            mii = i

    #print(ma, mai, mi, mii)


    B = A[::]
    ans = []
    for i in range(n):
        B[i] += B[mai]
        B[i] += B[mai]
        ans.append((i, mai))
        ans.append((i, mai))
        mai = i

    if check(B):
        out(ans)
        return


    B = A[::]
    ans = []
    for i in range(n - 1, -1, -1):
        B[i] += B[mii]
        B[i] += B[mii]
        ans.append((i, mii))
        ans.append((i, mii))
        mii = i

    if check(B):
        out(ans)
        return

    assert (False)


solve()