There may be other ways than this. If the file is large (MB or GB), you might not want this method. It reads the whole file into an array, @data, before printing. 
#!/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);
}

[download]
Chris

In reply to Re^3: Shorten a list... by Cristoforo
in thread Shorten a list... by la

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