Identify cell values

Hey Excel Maestros,

I have a quick question with identifying the values sitting in cells.

I have 2 columns in Sheet1. Column A has numbers listed from 1 to 20 sequentially. Column B has random numbers listed with duplicate values. Now if I pick a number from column B (lets say a 25 and it sits in cell B5 and B11 and B19) and pass it to a function then that function should return me the corresponding values of it with respect to column A that is the values sitting in cell numbers A5, A11 and A19 (which are 5,11,19 obviously). Also if I reference the number 25 to a different column lets say C1 and instead of passing 25 to the function I want to pass C1 even then it should return me 5,11,19.

Is a separate function required for this or is there something that already exists?

Thanks a bunch Again.

Special thanks to JBeaucaire for helping me with previous question.