my $test = "2123";
if($test=~/^\d{4}$/)
{    
          print "<td height=20 class=grtxt>0$test</td>\n";
}
else
{          
          print "<td height=20 class=grtxt>$test</td>\n";          
}

##</code><code>##

my $test = "2523";
$test = "0" . $test if($test=~/^\d{4}$/);
print "<td height=20 class=grtxt>$test</td>\n";