// meow.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>

using namespace std;

int main()
{
   
	double x, y, z;

	cin >> x >> y >> z;

	int a = (x + y + z) / 3;

	cout << a;
	
	
	
	return 0;
}