Need a help in c++ task about palindrome

Question

. So the task was to do a program that gets a word(min=2 letters, max=100000...). If the word is palindrome but it is written incorrectly, then is should print out the number of this incorrect letter counting from the left side to right( if u dont understand watch the example below ). And if the word is correct palindrome, then 0 should be printed out OR if this word is even not a palindrome(just a random word) then it prints out 0 too. So the condition that IF IT IS INCORRECT PALINDROME AND THERE IS ONLY ONE MISTAKE, THEN IS SHOULD PRINT OUT THE NUMBER OF THIS INCORRECT LETTER. EXAMPLE:: 1)U input racecazr(it is incorrect palindrome, so it will print out 7(as if 'z' will be removed ) it will be RACECAR ) 2) U input car (it prints out 0 as its just a word)

A palindrome is a word, that reads the same backward as forward. Cant even understand how to code this(maybe array of chars or something like this). Help please. I am really interested in it, but I DONT KNOW WHAT TO START WITH