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

Ex Input:
Sentence: 'a dog has found a rather large stick for playing fetch'. Find frequency of the letter 't'

Ex Output:
3


Ex Input:
Sentence: 'a man riding his skateboard down low as he turns'. Find frequency of the letter 'g'

Ex Output:
1


Ex Input:
Sentence: 'here is a kitten on the keys, keyboard, that is. this long-haired cat is sitting parallel to the top of the keyboard'. Find frequency of the letter 'e'

Ex Output:

11