# 1419. Minimum Number of Frogs Croaking

https://leetcode.com/problems/minimum-number-of-frogs-croaking

## Description

Given the string `croakOfFrogs`, which represents a combination of the string "croak" from different frogs, that is, multiple frogs can croak at the same time, so multiple “croak” are mixed. _Return the minimum number of_ different _frogs to finish all the croak in the given string._

A valid "croak" means a frog is printing 5 letters ‘c’, ’r’, ’o’, ’a’, ’k’ **sequentially**. The frogs have to print all five letters to finish a croak. If the given string is not a combination of valid "croak" return -1.

**Example 1:**

```
**Input:** croakOfFrogs = "croakcroak"
**Output:** 1 
**Explanation:** One frog yelling "croak**"** twice.
```

**Example 2:**

```
**Input:** croakOfFrogs = "crcoakroak"
**Output:** 2 
**Explanation:** The minimum number of frogs is two. 
The first frog could yell "**cr**c**oak**roak".
The second frog could yell later "cr**c**oak**roak**".
```

**Example 3:**

```
**Input:** croakOfFrogs = "croakcrook"
**Output:** -1
**Explanation:** The given string is an invalid combination of "croak**"** from different frogs.
```

**Example 4:**

```
**Input:** croakOfFrogs = "croakcroa"
**Output:** -1
```

**Constraints:**

* `1 <= croakOfFrogs.length <= 10^5`
* All characters in the string are: `'c'`, `'r'`, `'o'`, `'a'` or `'k'`.

## ac

```java
```
