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

[EX Q]: Sentence: 'four women around a man sitting in front of a cake'. Find frequency of the letter 'o'
[EX A]: 5

[EX Q]: Sentence: 'a man playing baseball on a television set'. Find frequency of the letter 'l'
[EX A]: 4

[EX Q]: Sentence: 'several umbrellas are on display in a storefront window'. Find frequency of the letter 'n'
[EX A]:
4