#include<bits/stdc++.h>
#define rep(i,a,n) for (int i = a;i < n;i++)
#define per(i,n,a) for (int i = n-1;i >= a;i--)
using namespace std;

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