#define _CRT_SECURE_NO_WARNINGS // #pragma warning(disable:4996)
#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <functional>
#include <sstream>
#include <cmath>
using namespace std; 

#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define pb push_back
#define mp(a,b) make_pair(a,b)
#define all(a) a.begin(),a.end()

typedef pair<int, int> Pii;
typedef vector<int> V;
typedef vector<V> VV;
typedef vector<VV> VVV;
typedef long long ll;
const int inf = 1e9;
const int mod = 1e9 + 7;

int main()
{
	int A[6];
	rep(i,0,6) cin >> A[i];
	sort(A,A+6);
	double sum = 0;
	rep(i,1,5) sum += A[i];
	printf("%.2f\n",sum/4);
	return 0;
}