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: Runtime Error)

N = int(input())
A = list(map(int,input().split()))

maxA,minA = max(A),min(A)
maxAi,minAi = -1,-1
sign = ""
M = []

for i in range(N):
    if A[i] == maxA:
        maxAi = i
        break
for i in range(N):
    if A[i] == minA:
        minAi = i
        break

if abs(maxA) >= abs(minA):
    A = list(map(lambda x: x+maxA, A))
    sign = "+"
else:
    A = list(map(lambda x: x+minA, A))
    sign = "-"

if sign == "+":
    for i in range(N):
        if i != maxAi:
            M.append((maxAi,i))
    M.append((maxAi,maxAi))
    for i in range(N-1):
        M.append((i,i+1))
elif sign == "-":
    for i in range(N):
        if i != minAi:
            M.append((minAi,i))
    M.append(minAi,minAi)
    for i in range(N-1):
        M.append((N-i,N-i-1))

L = len(M)
print(L)
for i in range(L):
    x,y = M[i]
    print(x,y)