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

Input: Consider Input: Sentence: 'a woman is taking a sip of a drink from a glass'. Find frequency of the letter 'i'

Output: 4


Input: Consider Input: Sentence: 'a man and a woman are walking down the street with an umbrella over their heads'. Find frequency of the letter 'w'

Output: 4


Input: Consider Input: Sentence: 'a small bus sitting in the lobby of a museum'. Find frequency of the letter 's'


Output: 4