def min(a,b); a < b ? a : b; end

N = gets.to_i
dp = Array.new(N + 1){Array.new(N + 1, 0)}
dp[0][0] = 1

(1 .. 2 * N).each do |n|
  (0 .. min(n, N)).each do |l|
    r = n - l
    if r > l
      dp[l][r] = 0
    else
      dp[l][r] = dp[l - 1][r] + dp[l][r - 1]
    end
  end
end
puts dp[N][N]