You need to use your understanding of the U$-$Net architecture to fill in missing elements of the

dimensions of the activation $($fasture$)$ maps at different levels of the encoder part, of the U$-$Net given in the

diagram below. At any Activation Map, the dimensions can be written as $($n x n x d$),$ where $\text{'}$n$\text{'}$ denotes the

lateral dimension $($assumed square$)$ and $\text{'}$d$\text{'}$ denotes the number of maps $($planes$).$ All dimensions on the

decoder side are provided, you need to use these to obtain the missing dimensions on the encoder side.

There are $4$ levels at the encoder side where the dimensions $-$ always in the generic form $($nnd$)-$ ar

missing, and these are denoted as C$1,$ C$2,$ C$3$ and C$4$ to the right of the shown maps, and Input, P$1,$ P$2$ and P$3$ to the left of the same maps. Note that from the information provided in the figure, all the eight missing tuples of $3$ numbers each can be deciphered. All you need to do is to provide these $8$ sets of $3$ numbers, to be written as:

Input $=$ na x na x da;