#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define Would
#define you
#define please

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	int S[6];
	rep(i, 6) cin >> S[i];
	sort(S, S + 6);

	int goukei = 0;
	for (int i = 1; i < 5; i++) goukei += S[i];

	double kotae = 1.0 * goukei / 4;

	cout << fixed << setprecision(2) << kotae << endl;


	Would you please return 0;
}