#include<iostream>
using namespace std;
class Sale
{
      private:
              int num;
              int quantity;
              float price;
              static int quantity_sum;
              static float price_total;
      public:
              Sale(int a,int b,float c):num(a),quantity(b),price(c){}
              void caculate();
              static void average();
      
};

void Sale::caculate()
{
    quantity_sum+=quantity;
    if(quantity<=10) price_total+=price*quantity;
    if(quantity>10) price_total=price_total+price*quantity*0.98;
     
}

void Sale::average()
{
    cout<<"the average price is :"<<price_total/quantity_sum<<endl;
}

int Sale::quantity_sum=0;
float Sale::price_total=0;
int main()
{   Sale today[3]={
                   Sale(101,5,23.5),
                   Sale(102,12,24.56),
                   Sale(103,100,21.5)
                   };
    int i;
    for(i=0;i<3;i++)
                    {
                    today[i].caculate();
                    }
                    
    Sale::average();
    system("pause");
    return 0;
    
    }