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

Ex Input:
Sentence: 'a couple of people that are on a baseball field'. Find frequency of the letter 'c'

Ex Output:
1


Ex Input:
Sentence: 'cars parked outside if a retail store'. Find frequency of the letter 'd'

Ex Output:
2


Ex Input:
Sentence: 'the two people are examining an object on a boat'. Find frequency of the letter 'h'

Ex Output:

1