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

[Q]: Sentence: 'a man and a woman are walking down the street with an umbrella over their heads'. Find frequency of the letter 'w'
[A]: 4


[Q]: Sentence: 'a young man with glasses on is taking a big bite'. Find frequency of the letter 's'
[A]: 4


[Q]: Sentence: 'there is an old stove with old pots on the burners'. Find frequency of the letter 't'
[A]:
5