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

Input: Consider Input: Sentence: 'two people under an umbrella while walking down a sidewalk'. Find frequency of the letter 'i'

Output: 3


Input: Consider Input: Sentence: 'town clocks affixed to a tall, brick building'. Find frequency of the letter 'r'

Output: 1


Input: Consider Input: Sentence: 'several boats in the water near two rock outcroppings'. Find frequency of the letter 'r'


Output: 5