package main

import (
	"fmt"
	"sort"
)

func main() {
	ss := make([]int, 6)
	for i := range ss {
		fmt.Scan(&ss[i])
	}
	sort.Ints(ss)
	var total float64
	for i := 1; i < len(ss)-1; i++ {
		total += float64(ss[i])
	}
	fmt.Printf("%.2f\n", total/4)
}