use File::Find;
my $filter =$ARGV[0] || '.' ;
my $deepest_path = '' ;
my $deepest = -1 ;
finddepth(\&wanted, '.');
print "$deepest_path\n" ;
sub wanted 
{
my $depth = $File::Find::name =~ tr[/][/] ;
if($File::Find::name =~ /$filter/o  && $depth > $deepest)
        {
        $deepest = $depth ;
        $deepest_path = $File::Find::name ;
        }
}