Road to Post Office

Vasiliy 要从家到 $d$ 千米远的警察局去，Vasiliy 有一辆车，但很破旧，每行驶 $k$ 千米就要坏掉，需修复 $t$ 秒才能重新启动，已知 Vasiliy 开车开 1 千米要 $a$ 秒，步行 1 千米要 $b$ 秒（$a < b$），Vasiliy 可以在任何一个时刻步行，请问 Vasiliy 最少要多少秒才能到达警察局。

Vasiliy has a car and he wants to get from home to the post office. The distance which he needs to pass equals to $ d $ kilometers. Vasiliy's car is not new — it breaks after driven every $ k $ kilometers and Vasiliy needs $ t $ seconds to repair it. After repairing his car Vasiliy can drive again (but after $ k $ kilometers it will break again, and so on). In the beginning of the trip the car is just from repair station. To drive one kilometer on car Vasiliy spends $ a $ seconds, to walk one kilometer on foot he needs $ b $ seconds ( $ a&lt;b $ ). Your task is to find minimal time after which Vasiliy will be able to reach the post office. Consider that in every moment of time Vasiliy can left his car and start to go on foot.

The first line contains 5 positive integers $ d,k,a,b,t $ ( $ 1<=d<=10^{12} $ ; $ 1<=k,a,b,t<=10^{6} $ ; $ a&lt;b $ ), where: - $ d $ — the distance from home to the post office; - $ k $ — the distance, which car is able to drive before breaking; - $ a $ — the time, which Vasiliy spends to drive 1 kilometer on his car; - $ b $ — the time, which Vasiliy spends to walk 1 kilometer on foot; - $ t $ — the time, which Vasiliy spends to repair his car.

Print the minimal time after which Vasiliy will be able to reach the post office.

5 2 1 4 10

14

5 2 1 4 5

13

In the first example Vasiliy needs to drive the first 2 kilometers on the car (in 2 seconds) and then to walk on foot 3 kilometers (in 12 seconds). So the answer equals to 14 seconds. In the second example Vasiliy needs to drive the first 2 kilometers on the car (in 2 seconds), then repair his car (in 5 seconds) and drive 2 kilometers more on the car (in 2 seconds). After that he needs to walk on foot 1 kilometer (in 4 seconds). So the answer equals to 13 seconds.