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

[Q]: Sentence: 'guy leans on truck's hood while taking pics next to parked motorcycles'. Find frequency of the letter 's'
[A]: 4


[Q]: Sentence: 'a group of people are playing soccer on a beach'. Find frequency of the letter 'l'
[A]: 2


[Q]: Sentence: 'a number of people in front of a building under a clock'. Find frequency of the letter 'b'
[A]:
2