#include <iostream>

using namespace std;

struct Person {
    char name[20];
    int age;
};

int main() {
    Person p[3];
    int sum = 0;

    for (int i = 0; i < 3; i++) {
        cin >> p[i].name;
        cin >> p[i].age;
        sum += p[i].age;
    }
    
    cout << sum / 3 << endl;
}