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

Ex Input:
Sentence: 'a woman sitting in front of a giant slice of cheese pizza'. Find frequency of the letter 'e'

Ex Output:
4


Ex Input:
Sentence: 'the interior of a living and dining room'. Find frequency of the letter 'i'

Ex Output:
6


Ex Input:
Sentence: 'several men in a striped colorful boat'. Find frequency of the letter 'l'

Ex Output:

3