instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'wooden and black bench on the side of the road'. Find frequency of the letter 'a'
answer:
3


question:
Sentence: 'a passenger bus that is driving down the street'. Find frequency of the letter 'r'
answer:
3


question:
Sentence: 'a man surfing on a wave in the ocean'. Find frequency of the letter 'g'
answer:

1