Google Spreadsheet - total of column if adjacent cell is true and minus another column

Google Spreadsheet - total of column if adjacent cell is true and minus another column

I have data like in the following table:
+---+-----+-----+
| A | B   | C   |
+---+-----+-----+
| 0 | 5   | 30  |
| 1 | 0   | 30  |
| 0 | 15  | 40  |
| 1 | 0   | 40  |
| 1 | 10  | 50  |
+---+-----+-----+
Column A is a flag (true = 1, false = 0) so we only add up rows with flag==1
Column B is a "tax" to remove from the amount in Column C
So basically here, the total would be 110:
(we don't count row 1)
30-0
(we don't count row 3)
40-0
50-10
How do I do it in Google Spreadsheet?