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

[EX Q]: Sentence: 'a silver train crossing the road on tracks'. Find frequency of the letter 'r'
[EX A]: 5

[EX Q]: Sentence: 'three people are gathered around sitting on a park bench'. Find frequency of the letter 'g'
[EX A]: 2

[EX Q]: Sentence: 'a young girl holds a teddy bear in front of the camera'. Find frequency of the letter 'r'
[EX A]:
4