// No.394 ハーフパイプ(1)
package main

import (
	"fmt"
	"slices"
)

func main() {
	var s = make([]int, 6)
	fmt.Scan(&s[0], &s[1], &s[2], &s[3], &s[4], &s[5])
	slices.Sort(s)
	fmt.Printf("%.2f\n", float64((s[1]+s[2]+s[3]+s[4]))/float64(4))
}