When sound travels through a gas, its speed depends primarily on the

density of the medium. The less dense the medium, the faster the speed

will be$.$ The following table shows the approximate speed of sound at $0$

degrees centigrade, measured in meters per second, when traveling through

carbon dioxide, air, helium, and hydrogen.

$---------------------------------------------$

Medium Speed $($Meters per Second$)$

$---------------------------------------$

Carbon Dioxide $258\mathrm{.}0$

Air $331\mathrm{.}5$

Helium $972\mathrm{.}0$

Hydrogen $1,270\mathrm{.}0$

$---------------------------------------------$

Write a program that displays a menu allowing the user to select one of

these four gases. After a selection has been made, the user should enter

the number of seconds it took for the sound to travel in this medium from

its source to the location at which it was detected.

The program should then report how far away $($in meters$)$ the source of

the sound was from the detection location.

Input Validation:

Check that the user has selected one of the available menu choices.

in c$++$