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

Ex Input:
Sentence: 'a young girl is brushing her teeth in this dated photo'. Find frequency of the letter 't'

Ex Output:
5


Ex Input:
Sentence: 'a woman is taking a sip of a drink from a glass'. Find frequency of the letter 'i'

Ex Output:
4


Ex Input:
Sentence: 'a red and white fire hydrant sitting in the middle of a forest'. Find frequency of the letter 's'

Ex Output:

2