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

Ex Input:
Sentence: 'a tennis player after hitting a shot back to the other side of the court'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'a woman walking on a shore next to a river'. Find frequency of the letter 'v'

Ex Output:
1


Ex Input:
Sentence: 'an entree of meat with noodles sitting across from a woman'. Find frequency of the letter 'a'

Ex Output:

5