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

[EX Q]: Sentence: 'a person is water skiing and there are birds flying around above them'. Find frequency of the letter 'n'
[EX A]: 5

[EX Q]: Sentence: 'a girl laying on a bed posing for a picture'. Find frequency of the letter 'i'
[EX A]: 4

[EX Q]: Sentence: 'several pedestrians walking with umbrellas on a rainy day'. Find frequency of the letter 'i'
[EX A]:
4