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

Ex Input:
Sentence: 'hotel towels with sunglasses perched and hotel business cards and catalog'. Find frequency of the letter 'o'

Ex Output:
4


Ex Input:
Sentence: 'a softball player holding the bat on first base'. Find frequency of the letter 't'

Ex Output:
4


Ex Input:
Sentence: 'a clock tower in the middle of a paved area in a park'. Find frequency of the letter 't'

Ex Output:

2