// The size field ends at the first space.
	nStr, rest, ok := strings.Cut(s, " ")
	if !ok {
		return "", "", s, ErrHeader
	}

	// Parse the first token as a decimal integer.
	n, perr := strconv.ParseInt(nStr, 10, 0) // Intentionally parse as native int
	if perr != nil || n < 5 || n > int64(len(s)) {
		return "", "", s, ErrHeader
	}

		fmt.Fprintln(os.Stderr, "reading input:", err)
	}
	fmt.Printf("%d\n", count)
	// Output: 15
}

// Use a Scanner with a custom split function (built by wrapping ScanWords) to validate
// 32-bit decimal input.
func ExampleScanner_custom() {
	// An artificial input source.
	const input = "1234 5678 1234567901234567890"
	scanner := bufio.NewScanner(strings.NewReader(input))

		return os.ErrInvalid
	}
	p := C.CString(s)
	defer C.free(unsafe.Pointer(p))
	if C.mpz_set_str(&z.i[0], p, C.int(base)) < 0 {
		return os.ErrInvalid
	}
	return nil
}

// String returns the decimal representation of z.
func (z *Int) String() string {
	if z == nil {
		return "nil"
	}
	z.doinit()
	p := C.mpz_get_str(nil, 10, &z.i[0])
	s := C.GoString(p)
	C.free(unsafe.Pointer(p))
	return s
}