#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < n; i++)
#define repp(i, n) rep(i, 0, n)
#define repb(i, a, b) for(int i = a; i >= b; i--)
#define all(a) a.begin(), a.end()
#define int long long
using namespace std;
typedef pair<int, int> P;

signed main(){
    vector<int> s(6);
    rep(i, 0, 6) cin >> s[i];
    sort(all(s));
    double sum = 0.0;
    rep(i, 1, 5) sum += s[i];
    printf("%.2lf\n", sum / 4.0);
}