What will be the output of the program?

#include<stdio.h>
#include<stdarg.h>
void fun(char *msg, ...);

int main()
{
    fun("ExamAdept", 1, 4, 7, 11, 0);
    return 0;
}
void fun(char *msg, ...)
{
    va_list ptr;
    int num;
    va_start(ptr, msg);
    num = va_arg(ptr, int);
    num = va_arg(ptr, int);
    printf("%d", num);
}

Which header file should you include, if you are going to develop a function, which can accept variable number of arguments?