#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(LL i = a;i<b; i++)
#define rrep(i,a,b) for(LL i = a;i>b; i--)
#define INF ((1LL<<62)-(1LL<<31))
#define ooki 9,223,372,036,854,775,807
#define tii -9,223,372,036,854,775,808
typedef long long LL;
int main(){
  vector<double> s(6);
 rep(i,0,6){cin>>s[i];}
  sort(s.begin(),s.end());
  cout<<fixed<<setprecision(2)<<(s[1]+s[2]+s[3]+s[4])/4<<endl;
}