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

Ex Input:
Sentence: 'a castle like bed room that has the era of templar knight similarities'. Find frequency of the letter 'm'

Ex Output:
3


Ex Input:
Sentence: 'different sets of luggage in a baggage claim area'. Find frequency of the letter 'r'

Ex Output:
2


Ex Input:
Sentence: 'a bath room with a sink and a mirror'. Find frequency of the letter 'a'

Ex Output:

5