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

Ex Input:
Sentence: 'two elephants facing each other touching trunks in an enclosure'. Find frequency of the letter 'f'

Ex Output:
1


Ex Input:
Sentence: 'a sheep in a field in front of other sheep'. Find frequency of the letter 'f'

Ex Output:
3


Ex Input:
Sentence: 'man standing in a family room with a game controller in his hand'. Find frequency of the letter 'n'

Ex Output:

7