Poodle and Bolonka
Poodle walks along the line segment parallel to the axis Ox (coordinates of one end-point are (x_1, y), coordinates of the other end-point are (x_2, y)). Initially, he is in the point (x_1, y) and goes to other end-point of the segment with velocity 1. When Poodle reaches the end-point (x_2, y), he immediately turns around and goes in the opposite direction with the same velocity 1 until he reaches the point (x_1, y). There he turns around again, goes in the direction of (x_2, y) again, etc.
Similarly, Bolonka walks along the line segment parallel to the axis Oy with end-points (x, y_1) and (x, y_2), starting from the point (x, y_1). She goes with velocity 1 as well and changes walking direction after reaching any end-point. They walk until they meet, i.e. come to same point at same time.
Your task is to determine how much time it will take (from start until the meeting moment).
Input
First line of input contains 3 integers x_1, x_2, y, and second line contains 3 integers x, y_1, y_2. All numbers do not exceed 5×10^8 by absolute value.
Output
Output only one number, time when Poodle and Bolonka meet for the first time. If they cannot met ever, output number −1.