import java.util.Scanner;

public class CaffeineLevels $\{$

public static void main$($String$[]$ args$)\{$

$//$ Create a scanner object to read input from the user

Scanner scnr $=$ new Scanner$($System$.$in$)$;

$//$ Declare a variable to store the initial caffeine level $($in mg$)$

double caffeineMg;

$//$ Prompt the user to enter the initial caffeine level

System.out.print$("$Enter the initial caffeine level $($in mg$)$: $")$;

$//$ Read the user's input and store it in the caffeineMg variable

caffeineMg $=$ scnr$.$nextDouble$()$;

$//$ Define the half$-$life of caffeine in hours

double halfLife $=6\mathrm{.}0$;

$//$ Calculate the caffeine level after $6$ hours using the half$-$life formula

double caffeineAfter$6$Hours $=$ caffeineMg $*$ Math.pow$(0\mathrm{.}5,6\mathrm{.}0/$ halfLife$)$;

$//$ Calculate the caffeine level after $12$ hours using the half$-$life formula

double caffeineAfter$12$Hours $=$ caffeineMg $*$ Math.pow$(0\mathrm{.}5,12\mathrm{.}0/$ halfLife$)$;

$//$ Calculate the caffeine level after $24$ hours using the half$-$life formula

double caffeineAfter$24$Hours $=$ caffeineMg $*$ Math.pow$(0\mathrm{.}5,24\mathrm{.}0/$ halfLife$)$;

$//$ Print the caffeine levels after $6,12,$ and $24$ hours with two decimal places

System.out.printf$("$After $6$ hours: $\%\mathrm{.}2$f mg

$",$ caffeineAfter$6$Hours$)$;

System.out.printf$("$After $12$ hours: $\%\mathrm{.}2$f mg

$",$ caffeineAfter$12$Hours$)$;

System.out.printf$("$After $24$ hours: $\%\mathrm{.}2$f mg

$",$ caffeineAfter$24$Hours$)$;