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: 'a child sitting a table with a pizza in front of him'. Find frequency of the letter 'h'

Ex Output:
3


Ex Input:
Sentence: 'a girl that has a kite in the air'. Find frequency of the letter 'r'

Ex Output:

2