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

Input: Consider Input: Sentence: 'a surfer is in the middle of an ocean wave'. Find frequency of the letter 'i'

Output: 3


Input: Consider Input: Sentence: 'a close up of a bird on the outside window sill'. Find frequency of the letter 'c'

Output: 1


Input: Consider Input: Sentence: 'a group of cows grazing in a densly grassy area'. Find frequency of the letter 'z'


Output: 1