There are two 100-story buildings, called A and B. (In this problem, the ground floor is called the first floor.)
For each $i = 1,\dots, 100$, the i-th floor of A and that of B are connected by a corridor.
Also, for each $i = 1,\dots, 99,$ there is a corridor that connects the (i+1)-th floor of A and the i-th floor of B.
You can traverse each of those corridors in both directions, and it takes you x minutes to get to the other end.
Additionally, both of the buildings have staircases. For each $i = 1,\dots, 99, a$ staircase connects the i-th and (i+1)-th floors of a building, and you need y minutes to get to an adjacent floor by taking the stairs.
Find the minimum time needed to reach the b-th floor of B from the a-th floor of A.

-----Constraints-----
- $1 \leq a,b,x,y \leq 100$
- All values in input are integers.

-----Input-----
Input is given from Standard Input in the following format:
a b x y

-----Output-----
Print the minimum time needed to reach the b-th floor of B from the a-th floor of A.

-----Sample Input-----
2 1 1 5

-----Sample Output-----
1

There is a corridor that directly connects the 2-nd floor of A and the 1-st floor of B, so you can travel between them in 1 minute.
This is the fastest way to get there, since taking the stairs just once costs you 5 minutes.

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