In this task, you need to count the number of times the given letter appears in the given sentence.

Sentence: 'a stop sign near a rail road crossing sign'. Find frequency of the letter 'g'
3

Sentence: 'man in a sleeping bag on the floor using a laptop computer'. Find frequency of the letter 'i'
3

Sentence: 'girl in dress flying colorful kite in cloudy sky'. Find frequency of the letter 'k'

2