주식 평균단가 계산기

* Main function:
When the market price is lower than the average unit price of stocks held
If you need to buy more, you can set the average unit price you want.
Calculate how many more weeks you need to buy.

* Add-ons:
1. If you enter the number of additional purchases, the average unit price after the additional purchases is calculated in advance.
2. Enter an additional purchase amount and it will calculate how many weeks you can add within the amount you entered.