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

[Q]: Sentence: 'a group of men standing on the side of a boat'. Find frequency of the letter 'o'
[A]: 5


[Q]: Sentence: 'two pepperoni pizzas and a cup on a counter'. Find frequency of the letter 'u'
[A]: 2


[Q]: Sentence: 'a man sets up a large flag on the beach while people look on'. Find frequency of the letter 'a'
[A]:
6