Creating an IF formula to convert a range of numbers from an adjacent column

I am using 16.56 Excel. I am trying to convert a column of numbers that range from 1 to 4. I want to be able to write an IF formula that can reverse convert the numbers into a new column.

So column B reads like the example below with the formulas in the cells in Column B.

I have the formula in B2 for reversing a single number eg =IF(A2=1,4).

However I need the IF formula to be able to cope with 1:4 and reverse the A number in all cases, i.e. 1:4

A           B

1           4          

2           3

3           2

4           1

I hope this makes sense and wondered if there was a solution out there??