[ Arithmetic. Mental calculation, etc. ]

An electronic clock shows hours and minutes (for example, 16:15). While practicing counting, Pinocchio finds the sum of the digits on the clock $(1+6+1+5=13)$. Write down the time of day when the sum of the digits on the clock will be the greatest.

#
No calculations or justifications were required from the students.

## Answer

$19: 59$.