import java.util.Scanner;

public class PrefixEvaluationTest $\{$

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

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

System.out.println$("$Prefix Evaluation $-$ Your Name"$)$;

String expression;

while $($true$)\{$

System.out.print$("$Enter an expression: $")$;

expression $=$ scanner.nextLine$().$trim$()$;

if $($expression$.$equalsIgnoreCase$("$done$"))\{$

break;

$\}$

int result $=$ eval$($expression$)$;

System.out.println$("$Evaluates to $"+$ result$)$;

$\}$

scanner.close$()$;

$\}$

public static int eval$($String e$)\{$

if $($isInteger$($e$))\{//$ Base case: if e is an integer

return Integer.parseInt$($e$)$;

$\}$ else $\{//$ Recursive case: e starts with $"("$

int endIndex $=$ e$.$indexOf$(\text{'}\text{'})$; $//$ Find the index of the space after the operator

char operator $=$ e$.$charAt$(1)$; $//$ Extract the operator

String rest $=$ e$.$substring$($endIndex $+1)$; $//$ Extract the rest of the expression

$//$ Parse operands recursively

String operand$1=$ rest.substring$(0,$ rest.indexOf$(\text{'}\text{'}))$;

String operand$2=$ rest.substring$($rest$.$indexOf$(\text{'}\text{'})+1)$;

int result $=0$;

$//$ Perform the operation based on the operator

if $($operator $==\text{'}+\text{'})\{$

result $=$ eval$($operand$1)+$ eval$($operand$2)$;

$\}$ else if $($operator $==\text{'}/\text{'})\{$

result $=$ eval$($operand$1)/$ eval$($operand$2)$;

$\}$

return result;

$\}$

$\}$

public static boolean isInteger$($String str$)\{$

try $\{$

Integer.parseInt$($str$)$;

return true;

$\}$ catch $($NumberFormatException e$)\{$

return false;

$\}$

$\}$

$\}$