def f(n)
  m = 2 * n
  ans = 0
  xs={}
  xs[0]=1
  m.times do
    ys = {}
    xs.keys.each do |x|
      if ys[x-1] == nil
        ys[x-1] = xs[x]
      else
        ys[x-1] += xs[x]
      end
      if ys[x+1] == nil
        ys[x+1] = xs[x]
      else
        ys[x+1] += xs[x]
      end
    end
    ans += ys[n] if ys[n] != nil
    xs = ys.clone
    xs[n] = 0
  end
  ans
end

p f(gets.to_i)