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

[EX Q]: Sentence: 'a man standing on a surf board in the ocean'. Find frequency of the letter 'f'
[EX A]: 1

[EX Q]: Sentence: 'a group of people are playing soccer on a beach'. Find frequency of the letter 'l'
[EX A]: 2

[EX Q]: Sentence: 'a woman seated at booth restaurant table, smiling and holding seasoning shaker over plate with slice of pizza, with a pan of pizza, another plate of pizza, and sodas in glasses on table'. Find frequency of the letter 's'
[EX A]:
12