# include <iostream>
# include <cstring>
# include <string>
# include <vector>
# include <cmath>
# include <sstream>
# include <iomanip>
# include <algorithm>
using namespace std;

# define repl(i, a, b)	for(int i=(int)(a);i<(int)(b);i++)
# define rep(i, n)	repl(i, 0, n)
typedef long long ll;

int main(){
	vector<int> v(6);
	rep(i, 6){
		cin >> v[i];
	}
	sort(v.begin(), v.end());

	int sum = 0;
	repl(i, 1, 5){
		sum += v[i];
	}
	cout << fixed << setprecision(10) << sum/4.0 << endl;
	return 0;
}