input: Write a function to solve the 0-1 Knapsack problem using a recursive approach. The function should return the maximum value that can be obtained with a given capacity of the knapsack. The input consists of a list of items, where each item is represented by a tuple containing its value and weight, and the capacity of the knapsack. The function should be named `knapSack` and should have parameters `W` (capacity of the knapsack), `wt` (list of weights), `val` (list of values), and `n` (number of items).
  
  assert knapSack(50, [10, 20, 30], [60, 100, 120], 3) == 220
  assert knapSack(10, [3, 4, 5], [10, 4, 7], 3) == 11
  assert knapSack(7, [4, 3, 2], [20, 15, 10], 3) ==25
  assert knapSack(0, [1, 2, 3], [5, 10, 20], 3) == 0
  assert knapSack(10, [], [], 0) == 0
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))
  