class Sum { 
    int n;
    float f() { 
       float sum=0;
       for(int i=1;i<=n;i++)
          sum=sum+i;
       return sum;  
    }
}
class Average extends Sum {
    int n;  
    float f() { 
      float c;
      super.n=n;
      c=super.f();
      return c/n; 
    }
   float g() {
       float c;
       c=super.f();
       return c/2; 
   }
}
public class Example5_7 {
   public static void main(String args[]) {
       Average aver=new Average();
       aver.n=100;
      
       float resultTwo=aver.g(); float resultOne=aver.f();
       System.out.println("resultOne="+resultOne);
       System.out.println("resultTwo="+resultTwo);
   }
}

class Student {
   int number;String name;
   Student() {
   }
   Student(int number,String name) {
      this.number=number;
      this.name=name;
      System.out.println("我的名字是:"+name+ "学号是:"+number);
   }
 }
class UniverStudent extends Student {
   boolean 婚否;
   UniverStudent(int number,String name,boolean b) {
      super(number,name);
      婚否=b;
      System.out.println("婚否="+婚否);
   }
}
public class Example5_8 {
   public static void main(String args[]) {
      UniverStudent zhang=new UniverStudent(9901,"何晓林",false);
   }
}