Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given a 0-indexed 2D integer array transactions, where transactions[i] = [costi, cashbacki].
The array describes transactions, where each transaction must be completed exactly once in some order. At any given moment, you have a certain amount of money. In order to complete transaction i, money >= costi must hold true. After performing a transaction, money becomes money - costi + cashbacki.
Return the minimum amount of money required before any transaction so that all of the transactions can be completed regardless of the order of the transactions.
 
Please complete the following python code precisely:
```python
class Solution:
    def minimumMoney(self, transactions: List[List[int]]) -> int:
```