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

Input: Consider Input: Sentence: 'two zebras standing around while a third zebra drinks from a pond'. Find frequency of the letter 's'

Output: 3


Input: Consider Input: Sentence: 'two bigger elephants standing with a small elephant'. Find frequency of the letter 't'

Output: 5


Input: Consider Input: Sentence: 'a guy surfs a wave in the ocean'. Find frequency of the letter 'v'


Output: 1