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: 'one man grabbing another at a table while laughing'. Find frequency of the letter 'n'

Ex Output:
5


Ex Input:
Sentence: 'tow birds flying by a long necked crane'. Find frequency of the letter 'f'

Ex Output:

1