src = float(input().strip())

croot = 0
eps = 1e-6
left, right = -3, 3
while abs(croot ** 3 - src) >= eps:
    c3 = croot ** 3
    if c3 < src:
        left = croot
        croot = (right + croot) / 2
    else:
        right = croot
        croot = (croot + left) / 2
print(f"{croot:.1f}")