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.