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

[Q]: Sentence: 'a man and a woman are walking down the street with an umbrella over their heads'. Find frequency of the letter 'w'
[A]: 4


[Q]: Sentence: 'baseball player reaching back as he's about to throw the ball'. Find frequency of the letter 'e'
[A]: 5


[Q]: Sentence: 'a baseball game is in motion as a batter takes a swing'. Find frequency of the letter 'i'
[A]:
4