$(document).ready(function() {
  $("#diners").validate({
    rules: {
      ime: "required",
      prezime: "required", 
      telefon: "required",
      destinacija: "required",
      iznos: {             // compound rule
      required: true,
      number: true
      },
      broj: {             // compound rule
      required: true,
      number: true,
      minlength: 12, 
      maxlength: 12
      },
      mail: {             // compound rule
      required: true,
      email: true
      }
    }    
  });
});