Greg Value

The Greg value of a number can be found by adding all the digits in an even position and subtracting all the digits in an odd position.

For example, the Greg value of \(456832\) is \((5+8+2) - (4+6+3) = 2.\)

A 12-digit number is to be formed by arranging these four cards:

Question:

What is the largest Greg value that can be obtained?