#!/usr/bin/perl
use strict;
use warnings;

my $hour = 0;
my @mins = ('00','05','10','15','20','25','30','35','40','45','50','55');
 
for my $hour (0..23){
  for (1..12 ){ 
    
    print $hour.':'.$mins[0],"\n"; 

push (@mins,shift(@mins)); #go round the clock
  }

}