- Prepare
- Algorithms
- Implementation
- Lisa's Workbook

# Lisa's Workbook

# Lisa's Workbook

Lisa just got a new math workbook. A workbook contains exercise problems, grouped into chapters. Lisa believes a problem to be *special* if its index (within a chapter) is the same as the page number where it's located. The format of Lisa's book is as follows:

- There are chapters in Lisa's workbook, numbered from to .
- The chapter has problems, numbered from to .
- Each page can hold
*up to*problems. Only a chapter's last page of exercises may contain fewer than problems. - Each new chapter starts on a new page, so a page
*will never*contain problems from more than one chapter. - The page number indexing starts at .

Given the details for Lisa's workbook, can you count its number of *special* problems?

**Example**

Lisa's workbook contains problems for chapter , and problems for chapter . Each page can hold problems.

The first page will hold problems for chapter . Problem is on page , so it is *special*. Page contains only Chapter , Problem , so no *special* problem is on page . Chapter problems start on page and there are problems. Since there is no problem on page , there is no *special* problem on that page either. There is *special* problem in her workbook.

**Note:** See the diagram in the *Explanation* section for more details.

**Function Description**

Complete the *workbook* function in the editor below.

workbook has the following parameter(s):

*int n:*the number of chapters*int k:*the maximum number of problems per page*int arr[n]:*the number of problems in each chapter

**Returns**

- *int:* the number of special problems in the workbook

**Input Format**

The first line contains two integers and , the number of chapters and the maximum number of problems per page.

The second line contains space-separated integers where denotes the number of problems in the chapter.

**Constraints**

**Sample Input**

STDIN Function ----- -------- 5 3 n = 5, k = 3 4 2 6 1 10 arr = [4, 2, 6, 1, 10]

**Sample Output**

```
4
```

**Explanation**

The diagram below depicts Lisa's workbook with chapters and a maximum of problems per page. Special problems are outlined in red, and page numbers are in yellow squares.

There are special problems and thus we print the number on a new line.