#!/usr/bin/perl -w
# Apply gravity to all uppercase characters such that they fall on top
# of non-whitespace characters.
#
# 2018-01-15

use strict;

my @lines = <>;
my $width = 0;
foreach (@lines)
{
   s/\s*$//s;
   $width = length($_) if $width < length($_);
}
foreach (@lines)
{
   $_ .= ' ' x ($width - length($_));
}

for(my $y = $#lines - 1; $y >= 0; $y--)
{
   for(my $x = 0; $x < $width; $x++)
   {
      my $c = substr($lines[$y], $x, 1);
      next unless $c =~ /[A-Z]/;
      for(my $d = $y; $d < $#lines; $d++)
      {
         last if substr($lines[$d + 1], $x, 1) ne ' ';
         substr($lines[$d], $x, 1) = ' ';
         substr($lines[$d + 1], $x, 1) = $c;
      }
   }
}
print "$_\n" foreach @lines;