Chocolates Parcel

Mubashir needs to assemble a parcel of ordered chocolates. He got two types of chocolates:

• Small chocolates (2 grams each)
• Big chocolates (5 grams each)

Create a function that takes three parameters: Number of small available chocolates n_small, number of big chocolates available n_big and desired weight (in grams) of the final parcel order.

The function should return the required number of small chocolates to achieve the goal. The function should return -1 if the goal cannot be achieved by any possible combinations of small and big chocolates.

Examples

chocolates_parcel(4, 1, 13) ➞ 4
# 4 small chocolates = 8 grams
# 1 big chocolate = 5 grams
# 8 + 5 = 13 grams
# Required number of small chocolates = 4

chocolates_parcel(4, 1, 14) ➞ -1
# You can not make any combination to reach 14 grams.

chocolates_parcel(2, 1, 7) ➞ 1
# 1 big chocolate = 5 grams
# 1 small chocolates = 2 grams
# 5 + 2 = 7 grams
# Required number of small chocolates = 1

Notes

• Maximize the use of big chocolates that are available to achieve the desired goal. And only then should you proceed to use the small chocolates.
• You can't break chocolates into small pieces.