**Time limit:**1.00 s**Memory limit:**512 MB

**Input**

The first input line has an integer $n$: the size of the array. The array elements are numbered $1,2,\dots,n$.

The next line has $n$ integers $x_1,x_2,\dots,x_n$: the contents of the array.

**Output**

First print an integer $k$: the number of reversals.

After that, print $k$ lines that describe the reversals. Each line has two integers $a$ and $b$: you reverse a subarray from position $a$ to position $b$.

**Constraints**

- $1 \le n \le 2 \cdot 10^5$

**Example**

Input:

`4`

2 3 1 4

Output:

`2`

1 3

2 3