input: Write a function to solve the 0-1 knapsack problem using a naive recursive approach.
  assert knapSack(50, [10, 20, 30], [60, 100, 120], 3) == 220
  assert knapSack(10, [5, 4, 6, 3], [10, 40, 30, 50], 4) == 90
  assert knapSack(7, [1, 3, 4, 5], [1, 4, 5, 7], 4) == 9
output: def knapSack(W, wt, val, n):
      # Base Case
      if n == 0 or W == 0:
          return 0
  
      # If weight of the nth item is more than Knapsack capacity W, then
      # this item cannot be included in the optimal solution
      if wt[n-1] > W:
          return knapSack(W, wt, val, n-1)
  
      # return the maximum of two cases:
      # (1) nth item included
      # (2) not included
      else:
          return max(
              val[n-1] + knapSack(W - wt[n-1], wt, val, n-1),
              knapSack(W, wt, val, n-1)
          )