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

Ex Input:
Sentence: 'this is a close up view of a tennis player during the game'. Find frequency of the letter 't'

Ex Output:
3


Ex Input:
Sentence: 'two men are playing a video game as another sits watching'. Find frequency of the letter 'a'

Ex Output:
7


Ex Input:
Sentence: 'a man with a pink shirt works on his laptop computer'. Find frequency of the letter 'o'

Ex Output:

4