构造函数中的Java枚举

我有一个枚举性别的类person,在person构造函数中,我要初始化性别和年龄。如何在main()方法中实例化一个新的Person?

class Person  {

   public enum Gender { M,F }

   int age;
   Gender gender;

   public Person(int age, Gender gender) {
       this.age=age; this.gender=gender;
   }           
}

public static void main(String[] args) {
    Person p = new Person(20, ?);        
}

顺致敬意,