package main

import (
	"fmt"
	"sort"
)

func main() {
	A := make([]int, 6)
	for i := 0; i < 6; i++ {
		fmt.Scan(&A[i])
	}
	sort.Ints(A)
	sum := 0
	for i := 1; i <= 4; i++ {
		sum += A[i] * 100
	}
	ave := sum / 4
	fmt.Print(ave / 100)
	fmt.Print(".")
	fmt.Printf("%02d", ave % 100)
	fmt.Println()
}