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

[EX Q]: Sentence: 'young boy flying kite in large field at outdoor event'. Find frequency of the letter 'y'
[EX A]: 3

[EX Q]: Sentence: 'a guy riding a bike close to a car in the street'. Find frequency of the letter 'i'
[EX A]: 4

[EX Q]: Sentence: 'a man holding a surfboard while standing in front of the ocean'. Find frequency of the letter 'r'
[EX A]:
3