Sorry i am new so i have no idea what you are talking about XD
My bad tho

First time ever that my solution matched with someone else ;
I am happy ;
Also Hello World

i was wondering that if sum is 10 then pre allocated memory became 3 or still 10?

EXAMPLE)
10NULL
OR
10NULL(some 7 gabages).

i solved it.

char *str = malloc(1); // working
char *str = malloc(0); // error

so it will be 10NULL. ok!