input: Write a function to calculate the maximum possible revenue from the items with given weights and values. The function should take three parameters: weights (a list of integers), values (a list of integers), and n (an integer representing the number of items). The function should return the maximum revenue achievable with a knapsack of capacity W=5.
  
  
  def knapsack(weights, values, n):
      # total capacity of knapsack
      W = 5
      
      # matrix to store solution matrix
      K = [[0 for x in range(W+1)] for x in range(n+1)]
      
      # build the solution matrix in bottom up manner
      for i in range(n+1):
          for w in range(W+1):
              if i==0 or w==0:
                  K[i][w] = 0
              elif weights[i-1] <= w:
                  K[i][w] = max(values[i-1] + K[i-1][w-weights[i-1]],  K[i-1][w])
              else:
                  K[i][w] = K[i-1][w]
      
      return K[n][W]
  
  assert knapsack([2, 1, 3], [4, 2, 3], 3) == 7
  assert knapsack([1, 2, 3], [6, 10, 12], 3) == 22
  assert knapsack([1, 1, 1], [5, 5, 5], 3) == 15
  assert knapsack([1], [1], 1) == 1
  assert knapsack([], [], 0) == 0
  
output: def knapsack(weights, values, n):
      W = 5
      K = [[0 for x in range(W+1)] for x in range(n+1)]
      
      for i in range(n+1):
          for w in range(W+1):
              if i==0 or w==0:
                  K[i][w] = 0
              elif weights[i-1] <= w:
                  K[i][w] = max(values[i-1] + K[i-1][w-weights[i-1]],  K[i-1][w])
              else:
                  K[i][w] = K[i-1][w]
      
      return K[n][W]