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

[EX Q]: Sentence: 'a train station with a train pulling into the platform'. Find frequency of the letter 'i'
[EX A]: 6

[EX Q]: Sentence: 'a group of cars and house on truck passing in a street'. Find frequency of the letter 'i'
[EX A]: 2

[EX Q]: Sentence: 'a vintage photo of man standing in the middle of some waves'. Find frequency of the letter 'f'
[EX A]:
2