from fractions import Fraction
num =int(input())
lst =[]
llst =[]
def inverse(f):
    return Fraction(f.denominator,f.numerator)
for y in range(num):
    if num % int(y+1) ==0:
        lst.append(y+1)
        y =Fraction(y,1)
        llst.append(inverse(y+1))

s = sum(lst)
su =sum(llst)
print(s/su)