#include <iostream>
using namespace std;

class Stdent {
private:
        int kor;
        int eng;
        int math;
public:
        Stdent(int k ,int e,int m){
            kor = k;
            eng = e;
            math= m;
        };
    float area(){
        float area = (kor + eng + math) / 3;
            return area;
        }
};

int main() {
    Stdent stdent(90,80,70);

    cout << stdent.area() <<endl;
    }