How to look HTML pattern Attribute in input

An input field that can contain only three letters (no numbers or special characters):

index.html

Example: HTML

 <form>
  <label for="country_code">Country code:</label>
  <input type="text" id="country_code" name="country_code"
  pattern="[A-Za-z]{3}" title="Three letter country code">
</form>

Output should be:

Type:	html
Category:	Web Tutorial
Sub Category:	HTML Input Attributes
Uploaded by:	Admin