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)

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


series_sorted = series[:]
series_sorted.sort()

def make_no_decrease(condition, series):
    if condition == 0:#正の整数列
        for i in range(1,N):
            print(i, i+1)
        print(N,N)
    elif condition == 1:#負の整数列
        for i in range(1,N):
            print(N-i, N+1)
            print(1,1)
            
if series_sorted[0]  >= 0: #正の時
    make_no_decrease(0, series)
    print(len(series))
elif series_sorted[-1] <= 0: #負の時
    make_no_decrease(1, series)
    print(len(series))
elif abs(series_sorted[-1]) <= abs(series_sorted[0]): #負の値のほうが大きい時
    print(2*len(series))
    min = series.index(series_sorted[0])
    for i in range(len(series)):
        print(min+1, i)
    make_no_decrease(1, series)
elif abs(series_sorted[0]) <= abs(series_sorted[-1]): #正の値のほうが大きい時
    print(2*len(series))
    max = series.index(series_sorted[-1])
    for i in range(len(series)):
        print(max+1, i+1)
    make_no_decrease(0, series)