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

Ex Input:
Sentence: 'oranges are sitting in a bowl on a table'. Find frequency of the letter 'a'

Ex Output:
5


Ex Input:
Sentence: 'a person holding onto a pink kite at the beach'. Find frequency of the letter 'n'

Ex Output:
4


Ex Input:
Sentence: 'a close up of a woman in pigtails a shirt and tie'. Find frequency of the letter 'i'

Ex Output:

5