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

my (@buffer, @data);
while (<DATA>) {
    if (/^Group/) {
        push @data, [@buffer] if @buffer > 2;
        @buffer = $_;   
    }
    else {
        push @buffer, $_;   
    }
}

push @data, [@buffer] if @buffer > 2;

{
	local $" = '';
	print join("\n", map "@$_", @data);
}