use warnings;
use strict;

my $infile  = 'D:/try_unicode/input.txt';  # or whatever
my $outfile = 'D:/try_unicode/output.doc';

open my $input,  '<:utf8', $infile  or die "Couldn't open file: $!";
open my $output, '>:utf8', $outfile or die "Couldn't open file: $!";

while (my $line = <$input>) {
    chomp $line;
    
    print $output 'The first four utf-8 chars from the line: ',
      pack( "U4", unpack( "U4", $line ) ),"\n";
      
    print $output 'Or, an easier way to get the same thing:  ',
      substr $line, 0, 4;
      
    print $output "\n", '-' x 79, "\n";
}