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

Input: Consider Input: Sentence: 'a group of men standing on the side of a boat'. Find frequency of the letter 'o'

Output: 5


Input: Consider Input: Sentence: 'two pepperoni pizzas and a cup on a counter'. Find frequency of the letter 'u'

Output: 2


Input: Consider Input: Sentence: 'the last octave of piano keys on a keyboard with a sound board'. Find frequency of the letter 'd'


Output: 3