D = 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991
N = int(input())
pre = len(str(D))
now = len(str(D*N))
if now - pre == 0:
    print("0." + str(N * D))
elif now - pre == 1:
    D = str(N * D)
    print(D[0] + "." + D[1:])
else:
    D = str(N * D)
    print(D[:2] + "." + D[2:])