#include<iostream>
using namespace std;

class Student{
public:
 Student(){
  number=0;
  grade=0;
 }
 Student(int n,int g):number(n),grade(g){};
 ~Student(){};
 int GetN(){return number;};
 int GetG(){return grade;};
private:
 int number;
 int grade;
};
class Calc{
public:
 Calc(){
  numberS=0;
 }
 void AddS(Student S);
 int sum();
private:
 Student student[50];
protected:
 int numberS;
};
class CalcEx:public Calc{
public:
 CalcEx(){};
 float Aver(){
  float aver=0;
  aver = sum()/(float)numberS;
  return aver;
 }
};
void Calc::AddS(Student S){
 student[numberS++]=S;
}
int Calc::sum(){
 int Sum=0;
 for(int i=0;i<numberS;i++){
  Sum += student[i].GetG();
 }
 return Sum;
}
int main(){
 Student stu1(1,30);
 Student stu2(2,90);
 Student stu3(3,100);
 Student stu4(4,50);
 
 CalcEx cal;
 cal.AddS(stu1);
 cal.AddS(stu2);
 cal.AddS(stu3);
 cal.AddS(stu4);
 cout<<"합계: "<<cal.sum()<<endl<<"평균: "<<cal.Aver()<<endl;
}

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클래스 Student와 Calc과 CalcEx를 이용해 성적의 합계와 평균을 구하고 출력한다.