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

Ex Input:
Sentence: 'a woman and a child walking down a street with a kite'. Find frequency of the letter 'n'

Ex Output:
4


Ex Input:
Sentence: 'a man hitting a tennis ball with a tennis racquet'. Find frequency of the letter 't'

Ex Output:
6


Ex Input:
Sentence: 'bright pink truck advertising allure parked in front of a building'. Find frequency of the letter 'o'

Ex Output:

2