B. Patrol
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

On a street represented as a straight line, a police officer patrols a section located between points with coordinates $$$A$$$ and $$$B$$$.

The patrolling is carried out under the following rules:

  1. At time $$$0$$$, the police officer is at point $$$A$$$.
  2. As soon as the police officer arrives at point $$$A$$$, he starts moving towards point $$$B$$$ at a speed of $$$1\, \mathrm{m/s}$$$.
  3. As soon as the police officer arrives at point $$$B$$$, he starts moving towards point $$$A$$$ at a speed of $$$1\, \mathrm{m/s}$$$.
  4. The change of direction is instantaneous.

At time $$$T$$$, the police officer receives a radio command to stop patrolling and proceed to point $$$C$$$, which is also located on the patrolled street. He immediately stops patrolling and begins to move towards point $$$C$$$ at a speed of $$$1\, \mathrm{m/s}$$$.

Input

In the first line, the coordinates of the patrolled section $$$A$$$ and $$$B$$$ are given ($$$0 \le A, B \le 10^5$$$, $$$A \ne B$$$).

In the second line, the moment of receiving the command $$$T$$$ ($$$0 \le T \le 10^9$$$) and the coordinate of point $$$C$$$ ($$$0 \le C \le 10^5$$$) are given.

All numbers in the input are integers. All coordinates are given in meters.

Output

Output the sought number of seconds from the moment of receiving the call to the moment the police officer arrives at point $$$C$$$.

Examples
Input
3 8
10 1
Output
2
Input
6 1
7 9
Output
6