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

[EX Q]: Sentence: 'a large grass pasture land with sheep grazing on grass'. Find frequency of the letter 'a'
[EX A]: 7

[EX Q]: Sentence: 'a close up of a train on a track in the dark'. Find frequency of the letter 'a'
[EX A]: 6

[EX Q]: Sentence: 'three adults sitting in a dark living room talking'. Find frequency of the letter 's'
[EX A]:
2