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

[Q]: Sentence: 'a  woman standing next to a man on a motorcycle in front of a market'. Find frequency of the letter 'l'
[A]: 1


[Q]: Sentence: 'a small dog sits in the rear window of a car'. Find frequency of the letter 'm'
[A]: 1


[Q]: Sentence: 'two males riding skateboards in a skate park'. Find frequency of the letter 's'
[A]:
4