In this task, you need to count the number of times the given letter appears in the given sentence.

[EX Q]: Sentence: 'a sheep in a field in front of other sheep'. Find frequency of the letter 'f'
[EX A]: 3

[EX Q]: Sentence: 'a airplane view of a big factory some people and cars'. Find frequency of the letter 'f'
[EX A]: 2

[EX Q]: Sentence: 'some players in action on the soccer field'. Find frequency of the letter 'o'
[EX A]:
4