#!/usr/bin/perl

use strict;
use warnings 'all';

my @arr1 = map {[split //]} <DATA>;
my @arr2 = map {my $n = $_; join "" => map {$_ -> [$n]} @arr1}
           0 .. @{$arr1 [0]} - 2;

print "$_\n" for @arr2;

__DATA__
ABC
DBC
ECC
FFF