#include <bits/stdc++.h>
#define rep(i,n) for(ll (i)=0;(i)<(n);(i)++)
#define repi(i,a,b) for(ll (i)=(a);(i)<(b);(i)++)
#define SIZE_OF_ARRAY(array)    (sizeof(array)/sizeof(array[0]))
typedef long long ll;
using namespace std;
int main(){
  vector<int> s(6);
  rep(i,6){
    cin >> s[i];
  }
  int min = *min_element(s.begin(),s.end());
  int max = *max_element(s.begin(),s.end());
  int sum = accumulate(s.begin(),s.end(),0);
  cout << fixed;
  cout << setprecision(2) << (double)(sum-min-max)/4 <<endl;
}