$1.$ Write a C$++$ program that does the following:

a$.$ Create a C$++$ file with the name problem$4.$cpp$.$

b$.$ Write the function unlucky$$using recursion, which returns true if the first two $($leftmost$)$ digits of the positive integer parameter add up to $13,$ else returns false.

c$.$ The function unlucky$$returns false if the parameter has fewer than $2$ digits.

d$.$ Type in the following main function into your C$++$ program file:

int main$()$

$\{$

$$int x $=6789$;

$$if $($unlucky$($x$))$ cout $<<$ x $<<"$ is Unlucky!

$"$;

$//$ prints $6789$ is Unlucky!

$$x $=6889$;

$$if $($unlucky$($x$))$ cout $<<$ x $<<"$ is Unlucky!

$"$;

$//$ prints nothing.

$$x $=6$;

$$if $($unlucky$($x$))$ cout $<<$ x $<<"$ is Unlucky!

$"$;

$//$ prints nothing.

$$x $=49$;

$$if $($unlucky$($x$))$ cout $<<$ x $<<"$ is Unlucky!

$"$;

$//$ prints $49$ is Unlucky!

$$

$$return $0$;

$\}$