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

[EX Q]: Sentence: 'two men sitting quietly on a park bench'. Find frequency of the letter 'a'
[EX A]: 2

[EX Q]: Sentence: 'a tennis player after hitting a shot back to the other side of the court'. Find frequency of the letter 'n'
[EX A]: 3

[EX Q]: Sentence: 'car straped on the back of a tow truck'. Find frequency of the letter 'n'
[EX A]:
1