#!/usr/bin/perl

use strict;
use warnings;
my $filename = '5678';
my %grades;
open(my $fh, '<:encoding(UTF-8)', $filename)
  or die "Could not open file '$filename' $!";


while (my $row = <$fh>)
{


     if ($row =~ /(\d+:\d+:\d+.\d+).(\d+)/)
     {
      $grades{"$1.$2"}{"time"} = $1 ;
      $grades{"$1.$2"}{"b"}    = $2 ;
     }
}

foreach my $name (sort keys %grades)
{

             print "$name: $grades{$name}{'time'}\n"

}
~