#include <iostream>
#include <vector>
#include <string>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)
#define dump(s) cerr << __LINE__ << "\t:" << #s << " = " << (s) << endl
    
using namespace std;

int main () {
    int sum = 0, mx = -1, mn = 1000;
    REP (i, 0, 6) {
	int score;
	cin >> score;
	sum += score;
	mx = max(mx, score);
	mn = min(mn, score);
    }
    sum -= (mx + mn);
    cout << sum / 4 << '.';
    sum %= 4;
    REP (i, 0, 2) {
	sum *= 10;
	cout << sum / 4;
	sum %= 4;
    }
    cout << endl;
    
    return 0; 
}