# 0482. License Key Formatting

https://leetcode.com/problems/license-key-formatting

## Description

You are given a license key represented as a string `s` that consists of only alphanumeric characters and dashes. The string is separated into `n + 1` groups by `n` dashes. You are also given an integer `k`.

We want to reformat the string `s` such that each group contains exactly `k` characters, except for the first group, which could be shorter than `k` but still must contain at least one character. Furthermore, there must be a dash inserted between two groups, and you should convert all lowercase letters to uppercase.

Return _the reformatted license key_.

**Example 1:**

```
**Input:** s = "5F3Z-2e-9-w", k = 4
**Output:** "5F3Z-2E9W"
**Explanation:** The string s has been split into two parts, each part has 4 characters.
Note that the two extra dashes are not needed and can be removed.
```

**Example 2:**

```
**Input:** s = "2-5g-3-J", k = 2
**Output:** "2-5G-3J"
**Explanation:** The string s has been split into three parts, each part has 2 characters except the first part as it could be shorter as mentioned above.
```

**Constraints:**

* `1 <= s.length <= 105`
* `s` consists of English letters, digits, and dashes `'-'`.
* `1 <= k <= 104`

## ac

```java
```
