# coding: utf-8

D = 0.1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991
d = 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991

N = int(input())
D *= N
d = str(d * N)

if D < 1:
    print("0." + d)
elif D < 10:
    print(d[0] + "." + d[1:])
elif D < 100:
    print(d[1] + "." + d[2:])