import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextDouble()) { // 注意 while 处理多个 case
            double a = in.nextDouble();
            double left = Math.min(a, -1);
            double right = Math.max(a, 1);
            double mid = 0.0;
            while((right - left) > 0.001){
                mid = left + (right - left)/2;
                if(mid * mid * mid > a){
                    right = mid;
                }else if(mid * mid * mid < a){
                    left = mid;
                }else{
                    System.out.print(mid);
                }
            }
            System.out.printf("%.1f",right);
        }
    }
}