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

Ex Input:
Sentence: 'the little girl is flying her kite in the field'. Find frequency of the letter 'i'

Ex Output:
7


Ex Input:
Sentence: 'a tennis player after hitting a shot back to the other side of the court'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'the bull is looking intensely into the camera'. Find frequency of the letter 'l'

Ex Output:

4