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

[Q]: Sentence: 'a birthday cake with a number one and three candle'. Find frequency of the letter 'w'
[A]: 1


[Q]: Sentence: 'flower in a vase full of water sitting on a stand '. Find frequency of the letter 'l'
[A]: 3


[Q]: Sentence: 'a sandwich view up very close, with wine behind it'. Find frequency of the letter 'y'
[A]:
1