[2000-01-01 00:00] Guard #1 begins shift
[2000-01-01 00:01] falls asleep
[2000-01-01 00:03] wakes up
[2000-01-02 00:00] Guard #1 begins shift
[2000-01-02 00:02] falls asleep
[2000-01-02 00:04] wakes up
[2000-01-03 00:00] Guard #2 begins shift
[2000-01-03 00:10] falls asleep
[2000-01-03 00:20] wakes up