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

a$.$ Create a C$++$ file with the name lab$13\_3.$cpp$.$

b$.$ Write the function bookEndString which has a string s and an integer r as parameters permanently

modifying the string s$.$ If the first and last letters of the string are the same, then add r copies of that letter

to the beginning and ending of the string. Otherwise, add r Z$\text{'}$s to the beginning and ending of the string.

c$.$ Write the main function that does the following:

i$.$ Prompt the user for a string containing at least $3$ letters, validating the input until the user enters

a string with at least $3$ letters.

ii$.$ Prompt the user for a positive integer, validating the input until the user enters a positive integer.

iii. Call the function bookEndString passing into it the string and the integer.

iv$.$ Print the modified string.

Sample run of the program:

Enter a word with at least three letters: hi

Invalid input! Enter a word with at least three letters: hello

Enter a number greater than $0$: $0$

Invalid input! Enter a number greater than $0$: $3$

The modified word is: ZZZhelloZZZ

Sample run of the program:

Enter a word with at least three letters: shoes

Enter a number greater than $0$: $4$

The modified word is: ssssshoesssss