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

[EX Q]: Sentence: 'the small black and white dog holds onto a frisbee'. Find frequency of the letter 'h'
[EX A]: 3

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

[EX Q]: Sentence: 'a cat standing on a toilet seat in a bathroom'. Find frequency of the letter 'm'
[EX A]:
1