#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <bitset>
using namespace std;

#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl

#define INF 1<<30


int main(){
    int s[6];
    int mn=INF, mx=-INF, sum=0;
    rep(i,6){
        cin>>s[i];
        mn=min(mn, s[i]);
        mx=max(mx, s[i]);
        sum+=s[i];
    }

    double res = 1.*(sum-mn-mx)/4.0;
    printf("%.2lf\n", res);


    return 0;
}