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:
N = int(input())
A = list(map(int, input().split()))
max_A = -10**9
max_num = 0
min_A = 10**9
min_num = 0
for i in range(N):
  if(max_A < A[i]):
    max_A = A[i]
    max_num = i
  if(min_A > A[i]):
    min_A = A[i]
    min_num = i
if(max_A > 0 and min_A < 0):
  if(abs(max_A) >= abs(min_A)):
    print(2*N-1)
    for i in range(N):
      A[i] += max_A
      print(max_num+1, i+1)
    for i in range(N-1):
      print(i+1, i+2)
  else:
    print(2*N-1)
    for i in range(N):
      A[i] += min_A
      print(min_num+1, i+1)
    for i in range(N-1, 0, -1):
      print(i+1, i)
elif(min_A >= 0):
  print(N-1)
  for i in range(N-1):
    print(i+1, i+2)
elif(max_A <= 0):
  print(N-1)
  for i in range(N-1, 0, -1):
    print(i+1, i)
else:
  print(0)