Using data-* to get the values of html tag

For example, i have this below code

  <ul data-country="A">
      <li data-province="1">USA</li>
      <li data-province="2">LA</li>
  </ul>
  <ul data-country="B">
      <li data-province="3">NY</li> 
  </ul>

How can i use javascript to get the value USA by using the data-attributes.

For example, by calling function getValue(‘A’,’1′) , i will get the return value of USA.