int var_accum(int (*f) (int, int), int count, ...)
{
    va_list args;
    va_start(args, count);

    int retval = 0;
    while(count--)
        retval = f(retval, va_arg(args, int));

    va_end(args);
    return retval;
}

int sum(int r, int n) { return r + n; }
int min(int r, int n) { return r < n ? r : n; }
int max(int r, int n) { return r > n ? r : n; }

#define sum(c, ...) var_accum(&sum, c, __VA_ARGS__);
#define min(c, ...) var_accum(&min, c, __VA_ARGS__);
#define max(c, ...) var_accum(&max, c, __VA_ARGS__);