An alternative is to use OFFSET:
Assuming the column value is stored in B1, you can use the following
C1 = OFFSET(A1, 0, B1 - 1)
This works by:
a) taking a base cell (A1)
b) adding 0 to the row (keeping it as A)
c) adding (A5 - 1) to the column
You can also use another value instead of 0 if you want to change the row value too.