excel validation rule

I have this formula in a cell of validation and I need it to let in a time in this format 12:00-18:00 which this current formula does but I need it to let in the word hol to

=IF(F4="",,(IF(OR(F4="Holi",AND(TIMEVALUE(TEXT((TIMEVALUE(RIGHT(F4,FIND("-",F4)-1))),"hh:mm"))=TIMEVALUE(RIGHT(F4,FIND("-",F4)-1)),TIMEVALUE(TEXT((TIMEVALUE(LEFT(F4,FIND("-",F4)-1))),"hh:mm"))=TIMEVALUE(LEFT(F4,FIND("-",F4)-1)))),TRUE,FALSE)))

thanks

No as the time in the cell is in the format of 12:00-18:00 and it would not check both times enter in the cell but I have work it out now

=IF(J6="",,IF(J6="Hol",TRUE,(IF(AND(TIMEVALUE(TEXT((TIMEVALUE(RIGHT(J6,FIND("-",J6)-1))),"hh:mm"))=TIMEVALUE(RIGHT(J6,FIND("-",J6)-1)),TIMEVALUE(TEXT((TIMEVALUE(LEFT(J6,FIND("-",J6)-1))),"hh:mm"))=TIMEVALUE(LEFT(J6,FIND("-",J6)-1))),TRUE,FALSE))))

thanks of trying to help