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

Ex Input:
Sentence: 'a woman holds the reins of a saddled horse'. Find frequency of the letter 'm'

Ex Output:
1


Ex Input:
Sentence: 'people plating cake in an office meeting room'. Find frequency of the letter 'g'

Ex Output:
2


Ex Input:
Sentence: 'a group of skiers are standing in the snow with their ski equipment'. Find frequency of the letter 'i'

Ex Output:

7