Description

You are now participating in a points race, which lasts for $X$ days. You can choose to participate in the training activities of the day and get $a$ points, or choose to sleep but lose $b$ points. But if you participate in the training activities for $k$ consecutive days, you will be forced to sleep for one day.

Your initial score is 0 points, and your score can be reduced to negative numbers during the race.

But the local environment is too bad, so you heard from other channels that you only need to get $Y$ points to advance to the next round.

You want to know, under the above conditions, how many days you need to get $Y$ points or above, and get the judgment that your score will not be greater than or equal to $Y$ points anyway.

Input

The first line contains three integers $X$ ($1\le X \le 300$), $a$, and $b$ ($1\le a,b\le 10^5$), representing the number of training days and the points you get if you participate in training and the points you lose if you are sleeping.

The second line contains two integers $k$ ($1\le k \le X$) and $Y$ ($1\le Y \le 10^9$), representing the training limit mentioned in the statement and the points you should get.

Output

Output one integer $t$, representing the minimum number of days that make your points over $Y$, or $-1$ if you can't make your points over $Y$ during the $X$ days.

Samples

20 10 5
4 100

13

20 10 5
10 200

-1

Resources

电子科技大学第十五届 ACM 趣味程序设计竞赛