How to make input text a non-editable and editable?

I want to make a line like "01-11-__-19" only the underline is editable" it can be any other number but the others is predefined code

i tried using the input tag "readonly value=" but all of them is read-only or disabled

<input type=\"text\" class=\"form-control\" inputmask=\"'mask': '__-__-__-__'\" value=\"" . $row["rhName"] . " NR " . "$row["rhOffice"]" . "-". $Month ."-225-". $Year . "\"> 

i expect the input disable the other number except the 225 in -225-