If 1e is your cost basis, then you need to enter that information.
Unless you know the cost basis, the amount is automatically zero. You will have to determine the sale category (long-term or short-term) based on when the stock was purchased.
When it comes to the date acquired, your 1099-B can still be useful (even though it left this area blank). As long as each sale was listed as either short-term or long-term, you can type in the word "Various" in the box for date acquired.
