"""samrium"""
import math
def sams():
    """Pukpik"""
    cho = float(input())
    pie = math.pi
    fff = (1 / (2 * pie)) * (math.sqrt(9.81 / cho))
    print("%.2f Hz"%fff)
sams()
9ac70e2bcbac750d182af9e8a7f0f4e7326013f2
<mask token>

<mask token>


def sams():
    """Pukpik"""
    cho = float(input())
    pie = math.pi
    fff = 1 / (2 * pie) * math.sqrt(9.81 / cho)
    print('%.2f Hz' % fff)


<mask token>

<mask token>


def sams():
    """Pukpik"""
    cho = float(input())
    pie = math.pi
    fff = 1 / (2 * pie) * math.sqrt(9.81 / cho)
    print('%.2f Hz' % fff)


sams()

<mask token>
import math


def sams():
    """Pukpik"""
    cho = float(input())
    pie = math.pi
    fff = 1 / (2 * pie) * math.sqrt(9.81 / cho)
    print('%.2f Hz' % fff)


sams()

"""samrium"""
import math
def sams():
    """Pukpik"""
    cho = float(input())
    pie = math.pi
    fff = (1 / (2 * pie)) * (math.sqrt(9.81 / cho))
    print("%.2f Hz"%fff)
sams()