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

Ex Input:
Sentence: 'bananas are being dried in a tropical setting'. Find frequency of the letter 'i'

Ex Output:
5


Ex Input:
Sentence: 'hotel towels with sunglasses perched and hotel business cards and catalog'. Find frequency of the letter 'o'

Ex Output:
4


Ex Input:
Sentence: 'the red fire truck heads out on a mission'. Find frequency of the letter 'u'

Ex Output:

2