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

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

Output: 3


Input: Consider Input: Sentence: 'a man sitting on a motorcycle near two other men'. Find frequency of the letter 'r'

Output: 3


Input: Consider Input: Sentence: 'cows standing on green grass with a fence and old building with towers in the background'. Find frequency of the letter 't'


Output: 5