The Blue Caterpillar Gives Advice#717
For a moment, Alice looked thoughtfully at the mushroom, trying to figure out which side was which; the mushroom was round, which left her completely puzzled. Finally, she made up her mind: she grasped the mushroom with both hands and broke off a piece from each side. It turned out that if you bite from the piece in the left hand, you can grow by inches, and if from the right hand – shrink by inches.
Help Alice determine if she can become inches tall, given her current height is inches.
The first line of the input file contains four numbers: , , , .
0 \leq |X|, |Y| \leq 10^6, 0 \leq |A|, |B| \leq 10^2.
Output a single integer – the minimum number of "bites" needed to reach the desired height, or -1 if it is impossible.
Example 1