Problem Description

ABC Zoo is the most popular zoo in the Takahashi Kingdom.

The admission fee at ABC Zoo is set as follows:

• Each child pays $A$ yen
• Each adult pays $B$ yen
• Groups with a total of $K$ or more people get a discount of $C$ yen per person

Now, a group consisting of $S$ children and $T$ adults is about to enter the zoo. Calculate the total admission fee this group must pay.

Input Format

The input is given from the standard input in the following format:

$A$ $B$ $C$ $K$ $S$ $T$

• The first line contains four integers $A, B, C, K$ separated by spaces, representing the price settings for the admission fee. The meanings of these variables are the same as in the problem statement. Each variable satisfies the following constraints:
• $0 ≦ C ≦ A ≦ B ≦ 1,000$
• $0 ≦ K ≦ 100$
• The second line contains two integers $S (0 ≦ S ≦ 100)$ and $T (0 ≦ T ≦ 100)$, representing the number of children and adults in the group, respectively.

Output Format

Output the total admission fee the group must pay in one line. End the output with a newline.

Sample Input and Output

Sample Input #1

100 200 50 20
40 10

Sample Output #1

3500

Sample Input #2

400 1000 400 21
10 10

Sample Output #2

14000

Sample Input #3

400 1000 400 20
10 10

Sample Output #3

6000

Notes/Hints

Sample Explanation 1

The group consists of 40 children and 10 adults. Since the total number of people is 20 or more, a discount of 50 yen per person is applied, totaling a discount of 2500 yen.

Sample Explanation 2

The total number of people in the group is not 21 or more, so no discount is applied.

见题面 Input 部分

见题面 Output 部分