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 ~l~, ~w~, ~d~, and ~t~, help Derek calculate how much time is needed to clear his driveway so he can get back to coding the next big game.

~l~, the length of his driveway in metres

~w~, the width of his driveway in metres

~d~, the depth of the snow in metres

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

Input Specification

There will be a 4 lines of input, ~l~, ~w~, ~d~, and ~t~.

~1 \le l,w,d,t \le 10^5~

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 ~3m * 4m * 0.5m~. It takes Derek 20 seconds per ~m^3~, so it takes him 120 seconds.