#include <iostream>
#include <algorithm>
#include <iomanip>

using namespace std;

int main()
{
  int in[6];
  double ave;
  for(int i=0; i<6; i++){
    cin>>in[i];
  }
  sort(in,in+(6));
  ave = (double(in[1])+double(in[2])+double(in[3])+double(in[4]))/4;
  cout<<fixed<<setprecision(2)<<ave<<endl;
  return 0;
}