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

[Q]: Sentence: 'a number of small boats on a beach near an umbrella'. Find frequency of the letter 's'
[A]: 2


[Q]: Sentence: 'a crowd of fans watch soccer players from stadium seating'. Find frequency of the letter 'f'
[A]: 3


[Q]: Sentence: 'a group of cows are grazing in the green grass'. Find frequency of the letter 'n'
[A]:
3