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

[Q]: Sentence: 'a view from a bathroom shows an open door'. Find frequency of the letter 'o'
[A]: 7


[Q]: Sentence: 'a group of cars and house on truck passing in a street'. Find frequency of the letter 'i'
[A]: 2


[Q]: Sentence: 'a person kite surfing in the ocean, with boats in the background'. Find frequency of the letter 'i'
[A]:
5