Lux pretty good at the math. And she is thinking about the prime question.
Lux want to find the two adjacent primes C1 and C2 (L<=C1< C2<=U) that are closest (i.e. C2-C1 is the minimum) and the two are most distance (i.e. C2-C1 is the maximun).
If there are other pairs that are the same distance apart, use the first pair.
2 17 14 17
2 3 7 11 -1