A 24-hour digital clock occasionally shows times that are palindromes such as 0:34:30, 21:33:12, and 1:20:21, if we ignore the colons.
What is the smallest interval between two such times?
Clarification: If the hour and/or minute and/or second have leading zeroes, only the leading zero for the hour is dropped. For example, one second after midnight would be displayed as 0:00:01.
Attribution: momath.org