package main

import (
	"fmt"
	"sort"
)

func main() {
	s := make([]int, 6)
	for i := 0; i < len(s); i++ {
		fmt.Scan(&s[i])
	}
	sort.Ints(s)
	s = s[1 : len(s)-1]
	var tot int
	for _, v := range s {
		tot += v
	}
	fmt.Printf("%.02f\n", float64(tot)/4)
}