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

[Q]: Sentence: 'a man riding his skateboard down low as he turns'. Find frequency of the letter 'g'
[A]: 1


[Q]: Sentence: 'a number of small boats on a beach near an umbrella'. Find frequency of the letter 's'
[A]: 2


[Q]: Sentence: 'woman seated on a park bench, reading and listening to music player'. Find frequency of the letter 'r'
[A]:
3