<s>[INST] We have 3 identical machines. Let’s denote them as M1, M2 and M3. These machines can be in two states – working or failed. In total, we have 6 hours and we want to work for 4 hours. If at any time M1 fails, we can’t use it again. M2 and M3 can be on for maximum 2 hours each. We can turn the machines on and off at any time.

How can we work for 4 hours, if M1 fails after 1 hour and M3 fails after 3 hours?[/INST]