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

[EX Q]: Sentence: 'a couple of girls are hanging out at a restaurant'. Find frequency of the letter 'l'
[EX A]: 2

[EX Q]: Sentence: 'a person riding a surfboard in the middle of a wave'. Find frequency of the letter 'o'
[EX A]: 3

[EX Q]: Sentence: 'group of players reaching for flying disc on playing field'. Find frequency of the letter 'g'
[EX A]:
4