instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a man serving himself pizza in a wooden booth'. Find frequency of the letter 'n'
answer:
4


question:
Sentence: 'a bus with two floors belonging to london country'. Find frequency of the letter 't'
answer:
4


question:
Sentence: 'a man swinging a tennis racket at a tennis ball'. Find frequency of the letter 'n'
answer:

7