A crossing controller has four states. After Red it goes to Red-and-amber, after Red-and-amber to Green, after Green to Amber, and after Amber back to Red. The machine is currently in Green. Order the next four states it enters.

1. Amber
2. Red
3. Red and amber together
4. Green

From Green the rules give Amber, then Red, then Red-and-amber, then Green again, the cycle closes after four ticks. Reading the rules in the order they are listed rather than following them from the given starting state is the trap; an FSM's behaviour depends on where it currently is, not on how the transitions happen to be written down.