Neural Net Exercise - Binary Encoder Network

4 input nodes, 2 hidden, 4 output.
Exemplars:

Input 1 0 0 0  Output 1 0 0 0
Input 0 1 0 0  Output 0 1 0 0
Input 0 0 1 0  Output 0 0 1 0
Input 0 0 0 1  Output 0 0 0 1

i.e. We simply want it to represent these 4 inputs somehow in just 2 hidden nodes.

Make the hidden nodes produce simply 0 or 1 output. Then Question:
After training: For each exemplar, what do the 2 hidden outputs y_j look like?