Some data which will help understand problem and test it!

Test:
2
40 223

Answer:
3
aromatize 1
dearomatize 1
take 2 1 2


Test:
3
50 55 158

Answer:
3
aromatize 2
dearomatize 1
take 3 1 2 3


Test:
4
100 512 128 146

Answer:
3
aromatize 1
dearomatize 2
take 4 1 2 3 4


Test:
2
100 135

Answer:
IMPOSSIBLE


Test:
2
400 31

Answer:
IMPOSSIBLE

Test:
2
100 171

Answer:
IMOSSIBLE

Thank you very much!

I got AC from first submit after my code finally work on all your test cases.