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

Ex Input:
Sentence: 'a group of people walking down a rain soaked street with umbrellas'. Find frequency of the letter 'w'

Ex Output:
3


Ex Input:
Sentence: 'a bathroom with a sink, counter top, and mirror is shown'. Find frequency of the letter 'i'

Ex Output:
4


Ex Input:
Sentence: 'two women standing beneath a white and blue umbrella'. Find frequency of the letter 'g'

Ex Output:

1