or download this
my($L,$b,$d)=@ARGV;opendir(DIR,"$L");@s=grep(!/^\.\.?$/,readdir(DIR));
+closedir(DIR);$b1=$b;for($p=$b;$p<=$d;$p++){$i=0;foreach(@s){$_=$s;if
+((/$b1/)||((/$p(?![0-9])/)&&(substr($',0,1)!~/[0-9]/)&&(substr($`,-1,
+1)!~/[0-9]/))){$i =1;}}print"$p\n"if($i eq 0);$b1++;}