#include<bits/stdc++.h>
#define rep(i, x) for(ll i = 0; i < x; i++)
#define rep2(i, x) for(ll i = 1; i <= x; i++)
#define all(a) (a).begin(),(a).end()
using ll = long long;
using ld = long double;
const ll INF = 10000000000000000;
using namespace std;
signed main() {
	cout << fixed << setprecision(15);
	
	ll n = 6, ave = 0; vector<ll> v(6);
	rep(i, n) { cin >> v[i]; }
	sort(all(v));
	rep2(i, n - 2) { ave += v[i]; }
	cout << ave / (ld)4 << endl;
	return 0;
}