conditional formatting using icons

i have an excel sheet consisting of start time and stop time columns and there is a column where it shows the difference between the time
for eg: Start time 11:00:00 and Stop time 11:30:00 so the difference is 0:30:00 in hh:mm:ss format.

i need to use conditional formatting on the third column with the set of icons meeting the conditions

if the time is = 0:30:00 then exclamation mark symbol (!)
if the time is < 0:30:00 then correct mark symbol
and if the time is > 0:30:00 then (X) mark symbol

please help !!!

Thank U very very much for the solution. i tried but couldn't get it right. Thank you again...