”あと何センチ近づけば良いんだろう”

What is the meaning of "良いん” in this sentence? I know that it means "good",
but this sentence is translated as:

"How many centimeters closer should I get?"

What function does “良いん” serve in the sentence?

Thanks
CC BY-SA 4.0
2023-03-02T23:40:50.130
98781
2023-03-02T23:40:50.130
55914
question
meaning usage
What is the meaning of "良いん in this sentence?