instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a silver train crossing the road on tracks'. Find frequency of the letter 'r'
answer:
5


question:
Sentence: 'a teddy bear is sitting on a heart shaped patio chair outside'. Find frequency of the letter 'i'
answer:
6


question:
Sentence: 'there is a plane flying in the sky'. Find frequency of the letter 'n'
answer:

3