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

[EX Q]: Sentence: 'a young elephant is touching a bigger elephant with its trunk'. Find frequency of the letter 'i'
[EX A]: 5

[EX Q]: Sentence: 'two men are playing a video game as another sits watching'. Find frequency of the letter 'a'
[EX A]: 7

[EX Q]: Sentence: 'a huge airplane flies over a string over some people'. Find frequency of the letter 'l'
[EX A]:
3