local str = "1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991"
local len = #str
local t, kuri = {}, {}
for i = 1, len do
  t[i] = tonumber(str:sub(len + 1 - i, len + 1 - i))
  kuri[i] = 0
end
kuri[len + 1], kuri[len + 2] = 0, 0
local n = io.read("*n")
for i = 1, len do
  local num = t[i] * n + kuri[i]
  t[i] = num % 10
  local kuri2 = math.floor(num / 100)
  kuri[i + 2] = kuri[i + 2] + kuri2
  kuri[i + 1] = kuri[i + 1] + math.floor((num - kuri2 * 100) / 10)
end
t[len + 1] = kuri[len + 1]
t[len + 2] = kuri[len + 2]
if(0 < t[len + 2]) then io.write(t[len + 2]) end
io.write(t[len + 1] .. ".")
for i = len, 1, -1 do
  io.write(t[i])
end
io.write("\n")