package main
import "fmt"
func main(){
var n float64
fmt.Scan(&n)
left , right := float64(-10000),float64(10000)
for right - left > 1e-8 {
mid := (left +right) / float64(2)
if mid * mid * mid >= n{
right = mid
}else{
left = mid
}
}
fmt.Printf("%f",left)
}