package main

import (
	"fmt"
	"sort"
)

func main() {
	s := make([]int, 6)
	for i := 0; i < 6; i++ {
		fmt.Scan(&s[i])
	}
	sort.Ints(s)
	m := s[1:5]
	fmt.Printf("%.2f\n", float64(sum(m))/4)
}

func sum(s []int) int {
	r := 0
	for _, v := range s{
		r += v
	}
	return r
}