class Yukicoder
  def initialize
    n = gets.to_i
    dp = Array.new(2*n+3, 0)

    dp[1] = 1
    dp[2] = 1

    1.upto(n) do |i|
      j = i*2

      j.downto(i) do |k|
        if dp[k] > 0
          dp[k+1] += dp[k]
          dp[k+2] = dp[k]
        end
      end
    end

    puts dp[n]
  end
end

Yukicoder.new