#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;

int main(){
    int t, sum1;
    vector<int> v(6);
    for (int i = 0; i < 6; i++) cin >> v[i];
    sort(v.begin(), v.end());
    for (int i = 1; i < 5; i++) sum1 += v[i];
    cout << fixed << setprecision(2) << (float)sum1/4 << endl;
}