Problem - USACO

I don’t understand why my code isn’t working on this problem. Can someone explain me what’s wrong with it?

```
import sys
x1a, y1a, x2a, y2a = list(map(int, sys.stdin.readline().split()))
x1b, y1b, x2b, y2b = list(map(int, sys.stdin.readline().split()))
x1c, y1c, x2c, y2c = list(map(int, sys.stdin.readline().split()))
first_area = abs(x2a - x1a) * abs(y2a - y1a)
second_area = abs(x2b - x1b) * abs(y2b - y1b)
intersect_first = abs(x2a - x1c) * abs(y2c - y1a)
intersect_second = abs(x2c - x1b) * abs(y2b - y1c)
final_area = (first_area - intersect_first) + (second_area - intersect_second)
print(final_area)
```