local n = io.read("*n")
local max = math.ceil(math.sqrt(n))
local found = false
for i = 3, max do
  if(n % i == 0) then
    print(i)
    found = true
    break
  end
end
if(not found) then
  if(n % 2 == 0 and 4 < n) then print(n / 2) else print(n) end
end