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

[Q]: Sentence: 'two baseball players high five each other during a game'. Find frequency of the letter 'y'
[A]: 1


[Q]: Sentence: 'an commercial airline airplane flies above the clouds'. Find frequency of the letter 'n'
[A]: 3


[Q]: Sentence: 'a person that is riding a motorcycle down the street'. Find frequency of the letter 'i'
[A]:
3