It's that time of the year again: WINTER! It has just snowed and Derek's driveway is covered in snow. It's Derek's job to shovel the snow but he hates doing it because it delays him from programming. Given , , , and , help Derek calculate how much time is needed to clear his driveway so he can get back to coding the next big game.

, the length of his driveway in metres

, the width of his driveway in metres

, the depth of the snow in metres

, the time (seconds) it takes to shovel 1 cubic metre

#### Input Specification

There will be a 4 lines of input, , , , and .

#### Output Specification

Output one number, rounded to **exactly one decimal point**, the number of seconds it takes for Derek to clear his driveway

#### Sample Input

```
3
4
0.5
20
```

#### Sample Output

`120.0`

#### Sample Explanation

The dimensions of the snow on his driveway is . It takes Derek 20 seconds per , so it takes him 120 seconds.

## Comments