#!/usr/bin/perl

use strict;
use warnings;

use List::Util qw/ max /;

my @rows; 
push @rows, [split (/\s/, $_)] for (<DATA>);
my $max_index = max map { scalar @$_ -1; } @rows;
for my $r (0..$max_index) {
   for my $c (0..$#rows) {
      print $rows[$c]->[$r] || ' ';
      print ' '; 
   }
   print "\n";
}

__DATA__
A B C F G
u b 
1 T A R S 2 P