instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'the two dogs are playing in the pen together'. Find frequency of the letter 'o'
answer:
3

question:
Sentence: 'a street scene looking at the back of the stop sign'. Find frequency of the letter 't'
answer:
6

question:
Sentence: 'many white birds flying above a river that flows in front of a forest'. Find frequency of the letter 'a'
answer:
5