#define _USE_MATH_DEFINES

#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max,count
#include <string>	//string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt
#include <sstream>	//stringstream,getline
#include <cmath>	//ceil,M_PI

using namespace std;


int main() {

	vector<int> S(6);
	for (int i = 0; i < 6; i++) {
		cin >> S[i];
	}

	sort(S.begin(), S.end());

	double sum = 0;
	for (int i = 1; i <= 4; i++) {
		sum += S[i];
	}

	double ans = sum / 4;
	cout << fixed << setprecision(2) << ans << endl;

	return 0;

}