Problem Statement

You are given a permutation $P=(P_1,P_2,\cdots,P_N)$ of $(1,2,\cdots,N)$. Additionally, you are given an integer $K$.

You can perform the following operation zero or more times:

• Choose integers $l$ and $r$ ($1 \leq l < r \leq N$). Here, the pair $(l,r)$ must satisfy all of the following conditions:
• $K \leq r-l$.
  • $P_l > P_r$ at the time of the operation.
  • The pair $(l,r)$ has never been chosen before.
• Then, swap the values of $P_l$ and $P_r$.

You want to maximize the number of operations. Find one way to achieve this.

Constraints

• $2 \leq N \leq 500$
• $1 \leq K \leq N-1$
• $(P_1,P_2,\cdots,P_N)$ is a permutation of $(1,2,\cdots,N)$.
• All input values are integers.

Input

The input is given from Standard Input in the following format:

N K
P_1 P_2 \cdots P_N

Output

Print the answer in the following format:

m
l_1 r_1
l_2 r_2
\vdots
l_m r_m

Here, $m$ is the maximum number of operations, and $l_i$ and $r_i$ are the values of $l$ and $r$ chosen in the $i$-th operation, respectively. If multiple solutions exist, you can print any of them.