n = gets.strip.to_i
D = "0.1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991"
#D = "0.12345"
ans = ""
num = 0
(1...D.length-1).each do |i|
	#print "#{D[-i, 1]}\n"
	num += D[-i, 1].to_i * n
	#print "#{num % 10}\n"
	ans = (num % 10).to_s + ans
	num /= 10
end
ans = num.to_s + "." + ans
puts ans