for (@$sur) {
    my $firstrow = join '<-->', @{$_}{qw/one two four/};
    $hash1{$_->{'three'}} .=
        $hash1{$_->{'three'}} ?
          '####'.$_->{'four'} :
          $firstrow;
}

##</code><code>##

$hash1{$_->{'three'}} .= $hash1{$_->{'three'}} ?
    '####' . $_->{'four'} :
    join( '<-->', @{$_}{qw/one two four/})
    for @$sur;