#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream> 
#include<map>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <iomanip>
using namespace std;
#define MAX_MOD 1000000007
#define REP(i,n) for(int i = 0;i < n;++i)
int main() {
	vector<double> s;
	REP(i, 6) {
		double hoge;
		cin >> hoge;
		s.push_back(hoge);
	}
	sort(begin(s), end(s));
	double ans = 0;
	for (int i = 1;i < 5;++i) {
		ans += s[i];
	}
	cout << fixed << setprecision(2) << ans/4<<endl;
	return 0;
}