#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <sstream>
#include <complex>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cmath>
#include <typeinfo>
#include <cassert>
#include <fstream>
#define REP(i,n) for(int i=0;i<n;i++)
#define FOR(i,a,b) for(int i = a;i<b;i++)
#define SSTR( x ) static_cast< std::ostringstream & >( \
        ( std::ostringstream() << std::dec << x ) ).str()
#define ALL(s) (s).begin(), (s).end()
using namespace std;
typedef long long unsigned int llu;
typedef long long ll;

int main (){
  int s;
  while (cin >> s){
    vector<int> as;
    as.push_back(s);
    double ans = 0;
    REP(i,5){
      int a;
      cin >> a;
      as.push_back(a);
    }
    sort(ALL(as));
    as.erase(as.begin());
    as.erase(as.end()-1);

    REP(i,4){
      ans += as[i];
    }
    ans /= 4;

    printf("%.2f\n",ans);
    as.clear();
  }
  return 0;
}