# Increasing Digits

Given an integer `n`

, return the number of positive integers of length `n`

such that the digits are strictly increasing.

https://binarysearch.com/problems/Increasing-Digits

## Examples

### Example 1

**Input**

- n =
`2`

**Output**

- answer =
`36`

**Explanation**

We have `12`

, `13`

, `14`

, …, `89`

.

### Example 2

**Input**

- n =
`1`

**Output**

- answer =
`9`

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