#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<cstring>
#include<cstdlib>
#include<string>
#include<numeric>
using namespace std;

#define int long long
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(v) (v).begin(),(v).end()
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;
template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}


signed main(){
    int a[6];
    rep(i,6)cin>>a[i];
    sort(a,a+6);
    printf("%.2f\n",accumulate(a+1,a+5,0ll)/4.0);
    return 0;
}