#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int,int>;
#define rep(i,n) for(int i=0;i<n;i++)

const ll mod = ll(1e9) + 7;
const int INF = 1<<29;

int main(){
    vector<int> a(6);
    rep(i,6) cin >> a[i];
    sort(a.begin(),a.end());
    int sum = 0;
    for (int i=1;i<5;i++){
        sum += a[i];
    }
    printf("%.2lf",sum/4.0);
    return 0;
}