Please solve the programming task below using a self-contained code snippet in a markdown code block.

Given a string text, you want to use the characters of text to form as many instances of the word "balloon" as possible.
You can use each character in text at most once. Return the maximum number of instances that can be formed.
 
Please complete the following python code precisely:
```python
class Solution:
    def maxNumberOfBalloons(self, text: str) -> int:
```