On checkered paper, Petya drew a segment from a point with coordinates (a,b) to a point with coordinates (c,d). How many cells does this segment pass through?
Input
Integers a, b, c, d are entered. Modulo numbers do not exceed 10
9.
Imprint
Print one number — the number of cells through which the segment passes.
Examples
| # |
Input |
Output |
| 1 |
0 0 6 4 |
8 |
| 2 |
3 3 -3 3 |
0 |