You are given a string croakOfFrogs representing a combination of sounds made by different frogs simultaneously croaking the word "croak". Multiple frogs can croak at the same time, resulting in their letters being interleaved.

A valid croak consists of the characters 'c', 'r', 'o', 'a', and 'k' produced in that exact sequential order. A single frog may croak multiple times, but it must complete all five characters of one croak before starting another.

Return the minimum number of distinct frogs required to produce the given string croakOfFrogs. If the string is not a valid sequence of croaks, return $-1$.

Constraints:

• $1 \leq$ croakOfFrogs.length $\leq 10^5$

• croakOfFrogs consists only of the characters 'c', 'r', 'o', 'a', and 'k'.

Input: croakOfFrogs = croak-str
Output: 1-int
Explanation: The string forms one complete croak, so only one frog is required.

Input: croakOfFrogs = ccrrooaakk-str
Output: 2-int
Explanation: Two croaks are interleaved, requiring two frogs to complete the sequence.

Input: croakOfFrogs = croaka-str
Output: -1-int
Explanation: The final a does not begin a complete croak, so the sequence is invalid.

Input: croakOfFrogs = crack-str
Output: -1-int
Explanation: The characters do not follow the required c, r, o, a, k order, so the sequence is invalid.

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