The Bishop's Colors

Difficulty: 1100 2000 ms 128 MB

math

A bishop moves diagonally any distance on an unbounded board. Minimum moves from (r1, c1) to (r2, c2), or −1 if impossible?

Input: one line with four integers r1 c1 r2 c2.

Output: 0, 1, 2 or −1.

Constraints:

• |coordinates| ≤ 10⁹

Sample Tests

1 1 3 3

1

1 1 1 2

-1

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