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

[Q]: Sentence: 'two zebras feed on a plant through some wire mesh'. Find frequency of the letter 'o'
[A]: 4


[Q]: Sentence: 'a girl sits on a surfboard and smiles'. Find frequency of the letter 'i'
[A]: 3


[Q]: Sentence: 'a fence with a blue umbrella hanging over the side of it'. Find frequency of the letter 'l'
[A]:
3