There are four groups of consecutive metals:
- Bronze
- Zinc
- Steel, Brass, Pewter
- Copper, Iron, Tin
From left to right, the display should look like:
- One of those four groups
- Empty slot
- One of those four groups
- Empty slot
- One of those four groups
- Empty slot
- The last of those four groups
Now figure out the order to put the groups in.
