N = int(input())

D = ""
for i in range(1,100):
    D += str(i)
D += "1"
D = int(D)
DN = D*N
DN = str(DN)
ans1 = DN[:3] + "." +DN[3:]
ans2 = DN[:2] + "." +DN[2:]
ans3 = DN[:1] + "." +DN[1:]
ans4 = "0." + DN
ans = [ans1,ans2,ans3,ans4]
for a in ans:
    if abs(float(a)-(D*N/(10**190))) < 1:
        print(a)
        exit()