I have syntax error when i execute littles programs (drag and drop) in C on fedora

["bastidesamuel@xxxxxxx" <bastidesamuel@xxxxxxx>]

I want to write littles programs in c on fedora
I have done 
vi prog
then 
chmod 755 prog

then i have drag and drop on "vi" some program of wiki dictionnary to
test that it work 

#include <stdio.h>
#include "math.h"

int main(void)
		{
  			printf("%d\n",add(3,5));
		}

but when I do ./prog
it return to me
./popo: line 4: syntax error near unexpected token `(' 
./popo: line 4: `int main(void)'


I tried to search with google the problem it tell me that i must put "return 0 ;" 
at the end but .. I have the same error i dont understand .

Thank you very much for help , sam ...