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

[EX Q]: Sentence: 'a log in the water with three birds perched on it'. Find frequency of the letter 'r'
[EX A]: 4

[EX Q]: Sentence: 'a truck is parked in front of a store'. Find frequency of the letter 't'
[EX A]: 3

[EX Q]: Sentence: 'a bull is standing in the middle of a street'. Find frequency of the letter 'e'
[EX A]:
4