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

my $string="perl monks"; 
$string =~ s/\s//;
my @splitted_string;
my @chars=split(//, $string);

for ($i=0;$i<=$#chars;$i++) {
    push (@splitted_string, $chars[$i].$chars[$i+1]); 
}

my $splitted_string = join(' ', @splitted_string);