class Solution:
  def countWays(self, n):
    
    def dp(acc, memo):
      if acc in memo:
        return memo[acc]
      if acc == n:
        return 1 
      if acc > n:
        return 0
      
      result = dp(acc + 1, memo) + dp(acc + 3, memo) + dp(acc + 4, memo)
      memo[acc] = result
      
      return result

    return dp(0, {})