The function millis$()$ returns an unsigned long integer equal to the number of

milliseconds since the last time the Arduino board was started $$ i$.$e$.,$ since a program

was downloaded or the board was powered up or the reset button was hit. If the

length of time exceeds the number of milliseconds that can be stored in an unsigned

long integer, then the returned value will $$rollover$$ to $0$ and you will not get an

accurate answer in the calling program.

a$)$ What is the longest duration of time that can be accurately determined if you

call millis$()$ like this:

unsigned long t $=$ millis$()$;

$($Express your answer in whatever unit is appropriate $$ minutes, hours, days,

etc.$)$