题解 | #求解立方根#

# import math

from decimal import Decimal


def main():
    a = input()
    # print(a)
    a = float(a)
    # b = math.pow(a, 1 / 3)
    # b = Decimal(b).quantize(Decimal("0.1"), rounding="ROUND_HALF_UP")

    # print(b)

    if abs(a) <= 20:
        if a >= 0:
            b = 0
            while b < 2.715:
                c = b * b * b
                if c >= a:
                    print(Decimal(b).quantize(Decimal("0.1"), rounding="ROUND_HALF_UP"))
                    break
                b += 0.01
        else:
            b = 0
            while b > -2.715:
                c = b * b * b
                if c <= a:
                    print(Decimal(b).quantize(Decimal("0.1"), rounding="ROUND_HALF_UP"))
                    break
                b -= 0.01


main()