$```$

public class Test $\{$

public static boolean calculate$($String s$,$ int start, int end$)\{$

if $($start $>=$ end$)\{$

return true;

$\}$ else if $($s$.$charAt$($start$)!=$ s$.$charAt$($end$))\{$

return false;

$\}$ else $\{$

return calculate$($s$,$ start $+1,$ end $-1)$;

$\}$

$\}$

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

boolean result$1=$ calculate$("$level$",0,4)$;

boolean result$2=$ calculate$("$aaaaaa$",0,4)$;

System.out.println$($result$1+"/"+$ result$2)$;

$\}$

$\}$

false$/$false

true$/$false

true$/$true

false$/$true

$```$