Assignment name  : biggest_pal
Expected files   : *.c, *.h
Allowed functions: write
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Write a program named biggest_pal that takes a string as argument and prints the
biggest palindrome included inside this string, followed by a newline. 

This string contains only lowercase characters.

If there is two palindromes of the same length, you have to print the last one.

If there is more or less than 1 argument, your program must print only a newline
only.

Exemples:

$> biggest_pal "abcba"
abcba
$> biggest_pal "aaaaaaaaaabbcbbaaaa"
aaaabbcbbaaaa
$> biggest_pal "aooibdaoiwhoihwdoinzeldaisaboyobasiadlezfdsfnslk"
zeldaisaboyobasiadlez
$> biggest_pal "aeibaabaammaabaalek"
aabaammaabaa
$> biggest_pal abeb qpinqwjobo qkmnwoiq

$> biggest_pal

$>