import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.text.DecimalFormat;

public class Main {

    public static void main(String[] args) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String str;
        while ((str = br.readLine())!=null) {
            double input = Double.parseDouble(str);
            DecimalFormat df = new DecimalFormat("#,#0.0");
            System.out.printf(df.format(getCubeRoot(input)));
        }
    }

    public static double getCubeRoot(double input) {
        /*在這里實(shí)現(xiàn)功能*/
        if (input == 0) {
            return 0;
        }
        double x0, x1;
        x0 = input;
        x1 = (2*x0 + input/x0/x0)/3;//利用迭代法求解
        while (Math.abs(x1 - x0) > 0.000001) {
            x0 = x1;
            x1 = (2*x0 + input/x0/x0)/3;
        }
        return x1;
    }
}

/*
    功能: 計(jì)算一個(gè)數(shù)字的四次方根
    輸入:double input 待求解參數(shù)
    返回值:double  輸入?yún)?shù)的四次方根
    */
    public static double getFour(double input) {
        /*在這里實(shí)現(xiàn)功能*/
        if (input == 0) {
            return 0;
        }
        double x0, x1;
        x0 = input;
        x1 = (3*x0 + input/x0/x0/x0) / 4;
        while (Math.abs(x1 - x0) > 0.000001) {
            x0 = x1;
            x1 = (3*x0 + input/x0/x0/x0) / 4;
        }
        return x1;
    }