input: Write a function to solve the 0-1 knapsack problem using a naive recursive approach. The function should take in the capacity of the knapsack, a list of item weights, a list of item values, and the number of items, and return the maximum value that can be obtained within the given capacity.
  
  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
  assert knapSack(3, [4], [5], 1)==0
output: def knapSack(capacity, weights, values, n):
      if n == 0 or capacity == 0:
          return 0
      if weights[n-1] > capacity:
          return knapSack(capacity, weights, values, n-1)
      else:
          return max(values[n-1] + knapSack(capacity-weights[n-1], weights, values, n-1),
                     knapSack(capacity, weights, values, n-1))