#!/usr/bin/perl -w
use strict;

sub time2num {
    my $time= shift(@_);
    my( $hr, $min, $sec, $dec )= split /[:.]/, $time;
    $dec= substr( $dec."0000", 0, 4 );
    return $dec + 10000*($sec+60*($min+60*$hr));
}

sub num2time {
    my $tick= shift(@_);
    my $sign= '+';
    if(  $tick < 0  ) {
        $sign= '-';
        $tick= -$tick;
    }
    my $sec= int( $tick/10000 );
    $tick %= 10000;
    my $min= int( $sec/60 );
    $sec %= 60;
    my $hr= int( $min/60 );
    $min %= 60;
    return sprintf "%s%d:%02d:%02d.%04d",
        $sign, $hr, $min, $sec, $tick;
}

my $diff= time2num('16:14:13.8167')
        - time2num('16:23:14.6152');
printf "%.4f\n", $diff/10000;
printf "%s\n", num2time($diff);