#include <iostream>
#include <iomanip>
#include <list>
using namespace std;


int main(){
    int j1,j2,j3,j4,j5,j6;
    cin >> j1 >> j2 >> j3 >> j4 >> j5 >> j6;
    list<int> jlist = {j1,j2,j3,j4,j5,j6};
    jlist.sort();
    jlist.pop_back();
    jlist.pop_front();
    int result = 0;
    list<int>::iterator it = jlist.begin();
    while( it != jlist.end() ){
        result += *it;
        ++it;
    }
    cout << fixed << setprecision(2) << (double)result / 4.00;
}