Draw a circuit that operates as follows:
When power is applied to the circuit and before any push buttons are pressed all relays are de-energised and lamps extinguished.
*Relay K1 is energised and latches by pressing PB S1.
*Relay K1 is de-energised by pressing PB S2.
*Relay K2 is energised by pressing PB S3.
*Relay K2 is de-energised by pressing PB S4.
*Relay K2 cannot energise unless K1 is energised.
*If relay K2 is energised, it will remain energised if K1 is de-energised.
*Lamp L1 illuminates when K1 is de-energised and lamp L2 illuminates when K2 is de-energised.