// No.1230 Hall_and_me
package main

import (
	"fmt"
)

func main() {
	var P, Q, R float64
	fmt.Scan(&P, &Q, &R)

	o := P
	if Q < o {
		o = Q
	}
	if R < o {
		o = R
	}

	fmt.Println(1.0 - o/(P+Q+R))
}