#!/usr/bin/perl

sub strip_plurel() 
{
    local $_ = $_[0];
    my @l;
    push @l, "$1y" if /^(.+)ies$/;
    push @l, "$1Y" if /^(.+)IES$/;
    push @l, $1    if /^(.+)es$/i;
    push @l, $1    if /^(.+)s$/i;
    return @l;
}

if ($#ARGV == -1) {
    $in = STDIN;
} else {
    $in = "IN";
    open $in, $ARGV[0] or die;
}

while (<$in>) {
    chop;
    $lookup{$_} = 1;
}

if ($#ARGV == -1) {
    $out = STDOUT;
} else {
    close $in;
    $out = "OUT";
    open $out, ">$ARGV[0]" or die;
}

foreach $w (keys lookup) 
{
    my $dont_print = 0;
    foreach $s (&strip_plurel($w)) 
    {
	if (exists $lookup{$s}) 
	{
	    $dont_print = 1;
	}
    }
    print $out "$w\n" unless $dont_print;
}