instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a red and white train passing a train station'. Find frequency of the letter 'a'
answer:
7


question:
Sentence: 'a girl laying on a bed posing for a picture'. Find frequency of the letter 'i'
answer:
4


question:
Sentence: 'two sheep wearing white covering in a stable'. Find frequency of the letter 's'
answer:

2