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 PYTHON3):

Solution:
from collections import Counter

N = int(input())
a = [int(i) for i in input().split()]

schedule = []
m = 0
if -min(a) > max(a) :
    mv = min(a)
    mi = a.index(mv)
    
    for i in range(N-2, -1, -1) :
        while a[i] > a[i + 1] :
            a[i] += mv
            schedule.append([mi+1, i+1])
            if a[i] < mv :
                mv = a[i]
                mi = i
            m += 1
else :
    Mv = max(a)
    Mi = a.index(Mv)
    
    for i in range(1, N) :
        while a[i-1] > a[i] :
            a[i] += Mv
            schedule.append([Mi+1, i+1])
            if a[i] > Mv :
                Mv = a[i]
                Mi = i
            m += 1

print(m)
for sch in schedule :
    print(*sch)