package main

import (
	"fmt"
	"math"
)

func main() {
	var n, g, v int
	_, _ = fmt.Scan(&n, &g, &v)
	ng := g * (n / 5)
	fmt.Print(ng / v)
	if ng%v != 0 {
		fmt.Printf(".%d", ng%v*int(math.Pow10(12))/v)
	}
	fmt.Printf("\n")
}