instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a log in the water with three birds perched on it'. Find frequency of the letter 'r'
answer:
4


question:
Sentence: 'a yellow fire hydrant in the forefront of a roadway'. Find frequency of the letter 'r'
answer:
5


question:
Sentence: 'an commercial airline airplane flies above the clouds'. Find frequency of the letter 'n'
answer:

3