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

[Q]: Sentence: 'some giraffes moving across a big grass field'. Find frequency of the letter 'e'
[A]: 3


[Q]: Sentence: 'soccer players on opposite teams fight for control over a ball'. Find frequency of the letter 't'
[A]: 4


[Q]: Sentence: 'people walk on the sidewalk near the red traffic light'. Find frequency of the letter 'i'
[A]:
3