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

Ex Input:
Sentence: 'a doll with huge eyes and black hair with blunt bangs holds a red umbrella'. Find frequency of the letter 'e'

Ex Output:
5


Ex Input:
Sentence: 'a blue train on a track next to another track'. Find frequency of the letter 'c'

Ex Output:
2


Ex Input:
Sentence: 'an object floating in a large body of water'. Find frequency of the letter 'n'

Ex Output:

3