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

[EX Q]: Sentence: 'two people under an umbrella while walking down a sidewalk'. Find frequency of the letter 'i'
[EX A]: 3

[EX Q]: Sentence: 'a man walking a large elephant down a dirt road'. Find frequency of the letter 'g'
[EX A]: 2

[EX Q]: Sentence: 'a night view of street lights and lamps'. Find frequency of the letter 'h'
[EX A]:
2