Problem Statement

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.