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

[EX Q]: Sentence: 'a man in a black wet suit rides an orange surfboard on the water'. Find frequency of the letter 'o'
[EX A]: 3

[EX Q]: Sentence: 'a small doughnut held in a persons hand'. Find frequency of the letter 'n'
[EX A]: 4

[EX Q]: Sentence: 'two people holding a glass and smiling at the camera and one man looking confused'. Find frequency of the letter 'm'
[EX A]:
3