input: def knapSack(W, wt, val, n):
      """
      Find the optimal solution to the 0-1 Knapsack problem using a naive recursive approach.
      
      >>> knapSack(50, [10, 20, 30], [60, 100, 120], 3)
      220
      >>> knapSack(10, [5, 4, 6, 3], [10, 40, 30, 50], 4)
      90
      """
output:     
      if n == 0 or W == 0:
          return 0
      
      if wt[n-1] > W:
          return knapSack(W, wt, val, n-1)
      else:
          return max(val[n-1] + knapSack(W-wt[n-1], wt, val, n-1), knapSack(W, wt, val, n-1))
  