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

[Q]: Sentence: 'two people and two children walking in a building'. Find frequency of the letter 'd'
[A]: 3

[Q]: Sentence: 'a photo of a small boat on a shore'. Find frequency of the letter 'f'
[A]: 1

[Q]: Sentence: 'a person's hand on a suitcase that is open'. Find frequency of the letter 'h'
[A]:
2