#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
#define pb push_back
#define mp make_pair
#define fi first
#define se second

int main()
{
	double a[6],sum=0;
	for(int i=0;i<6;i++)cin>>a[i];
	sort(a,a+6);
	for(int i=1;i<5;i++)sum+=a[i];
	cout<<fixed<<setprecision(2)<<sum/4<<endl;
	return 0;
}