import java.util.; import java.io.; public class Main{ public static void main(String[] args)throws IOException{ BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); String str = null; while((str = in.readLine()) != null){ Double num = Double.parseDouble(str); double x0 = num; double x1 = (2 * x0 + num /(x0 * x0))/3; while(Math.abs(x1 - x0) > 0.00001){ x0 = x1; x1 = (2 * x0 + num /(x0 * x0))/3; } System.out.println(String.format("%.1f",x1)); } } }