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

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

Sentence: 'a herd of giraffe walking across a field'. Find frequency of the letter 'k'
1

Sentence: 'birds are sitting on an automobile where a woman is sitting'. Find frequency of the letter 'a'

5