#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    
    double ans = 0;
    vector<int> s(6);
    for ( int i = 0; i < 6; i++ ) {
        cin >> s[i];
    }
    
    sort( s.begin(), s.end() );
    
    for ( int i = 1; i < 5; i++ ) {
        ans += s[i];
    }
    
    printf( "%f", ans/4 ); 
    
    return 0;
}