d = '1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991'

def readint():
    return int(input())

def main():
    n = readint()

    x = int(d)
    y = x * n

    m = len(str(y)) - len(d)

    a = str(y)[:m]
    b = str(y)[m:]
    if len(a) == 0:
        a = '0'
    print("%s.%s" % (a, b))

main()