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 (2.7.6) (judge verdict: Runtime Error)

import heapq
N=input()
#print N
a=[]
a=map(int,raw_input().split())
#print a

q1=[] #+
q2=[] #-
for ind,i in enumerate(a):
	if i>=0:
		heapq.heappush(q1, [-1*i,ind])
	else:
		heapq.heappush(q2, [i,ind])
#print "# q1"	
#print q1
#print "# q2"
#print q2

cnt=0
b=[]
for ind,i in enumerate(a):
	if ind==0:
		prev_i=i
		continue
	else:
		if prev_i<=i:
			prev_i=i
			continue
		else:
			#print ind,prev_i,i
			#while prev_i>i:
			if i<0 and prev_i<0:
				t_val=q2[0][0]
				#prev_i+=t_val
				cnt=cnt+(abs(i-prev_i)/t_val)+1
				#print (abs(i-prev_i)/t_val),cnt
				for i in range( (abs(i-prev_i)/t_val)+1 ):
					b.append((q2[0][1]+1,ind))
			else:
				t_val=q1[0][0]
				#i-=t_val
				cnt=cnt+(abs(i-prev_i)/t_val)+1
				#print cnt
				for i in range( (abs(i-prev_i)/t_val)+1 ):
					b.append((q1[0][1]+1,ind+1))

	

print cnt
#print b
for i,j in b:
	print i,j