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

Ex Input:
Sentence: 'two zebras feed on a plant through some wire mesh'. Find frequency of the letter 'o'

Ex Output:
4


Ex Input:
Sentence: 'a tall building with antenna stands before a jet flying in the background'. Find frequency of the letter 't'

Ex Output:
6


Ex Input:
Sentence: 'a lit candle is on a table where red wine is being poured into a glass'. Find frequency of the letter 's'

Ex Output:

4