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

[EX Q]: Sentence: 'a man flying through the air on top of a skateboard'. Find frequency of the letter 'h'
[EX A]: 3

[EX Q]: Sentence: 'a dog laying on the back of a boat in the water'. Find frequency of the letter 't'
[EX A]: 4

[EX Q]: Sentence: 'an orange fire hydrant sitting at the side of the street'. Find frequency of the letter 'i'
[EX A]:
4