Finding the area of a rectangle in python
To calculate the area of a rectangle on a coordinate system, you need the length between x1 and x2, and the length between y1 and y2.
x1 = int(input())
y1 = int(input())
x2 = int(input())
y2 = int(input())

xDiff = abs(x1 - x2) # Using absolute value to ignore negatives
yDiff = abs(y1 - y2)

area = xDiff * yDiff

Edit: Forgot to mention, if x2 is always greater than x1, and y2 is always greater than y1, instead you can just use xDiff = x2 - x1 and yDiff = y2 - y1