4:2 adder project 4

Hi, in project 4 in the implementation of 4:2 adder there should be 18 output bits in S and C (the outputs), while in the the template given to us there were only 16 bits.
I saw the email that was sent regarding this issue but it is still unclear to me- Can you please specify exactly what should the outputs be?
If the outputs are be S[X:Y], C[W, K]- what should X, Y, W, K should be?

In general, a 4:2-adder for addends of length n has outputs of length n+2.
However, we are using them for a multiplier. The multiplier has operands that are 8 bits long.
Hence, the product can be represented in binary using 16 bits.
This means that we need not output the 2 extra bits of the 4:2 adder (because they will always be zero!).