N
A1 A2 A3 ... AN

func main() {
	N := // Nの入力を受け付ける・・・①
	if N > int(3*(math.Pow(10, 6))) {
		log.Fatalf("Regulation error: N => %d\n", N)
		return
	}

	A_list := make([]int, N)
	for i := 0; i < N; i++ {
		A_list[i] = // Aの入力を受け付ける・・・②
	}
}

// Scan scans text read from standard input, storing successive
// space-separated values into successive arguments. Newlines count
// as space. It returns the number of items successfully scanned.
// If that is less than the number of arguments, err will report why.
//
func Scan(a ...any) (n int, err error) {
	return Fscan(os.Stdin, a...)
}

// Fscan scans text read from r, storing successive space-separated
// values into successive arguments. Newlines count as space. It
// returns the number of items successfully scanned. If that is less
// than the number of arguments, err will report why.
func Fscan(r io.Reader, a ...any) (n int, err error) {
	s, old := newScanState(r, true, false)
	n, err = s.doScan(a)
	s.free(old)
	return
}

// Scanner provides a convenient interface for reading data such as
// a file of newline-delimited lines of text. Successive calls to
// the Scan method will step through the 'tokens' of a file, skipping
// the bytes between the tokens. The specification of a token is
// defined by a split function of type SplitFunc; the default split
// function breaks the input into lines with line termination stripped. Split
// functions are defined in this package for scanning a file into
// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
// client may instead provide a custom split function.
//
type Scanner struct {
	r            io.Reader // The reader provided by the client.
	split        SplitFunc // The function to split the tokens.
	maxTokenSize int       // Maximum size of a token; modified by tests.
	token        []byte    // Last token returned by split.
	buf          []byte    // Buffer used as argument to split.
	// 以下, 省略
}

// SplitFunc is the signature of the split function used to tokenize the input.
type SplitFunc func(data []byte, atEOF bool) (advance int, token []byte, err error)

// バイト毎
func ScanBytes(data []byte, atEOF bool) (advance int, token []byte, err error)

// 行毎
func ScanLines(data []byte, atEOF bool) (advance int, token []byte, err error)

// ルーン（int32のエイリアス）毎
func ScanRunes(data []byte, atEOF bool) (advance int, token []byte, err error)

// 単語毎
func ScanWords(data []byte, atEOF bool) (advance int, token []byte, err error)

// NewScanner returns a new Scanner to read from r.
// The split function defaults to ScanLines.
func NewScanner(r io.Reader) *Scanner

// Split sets the split function for the Scanner.
// The default split function is ScanLines.
func (s *Scanner) Split(split SplitFunc)

N
A1 A2 A3 ... AN

// スキャナを作成
var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Split(bufio.ScanWords) // 単語（空白スペース）で分割
    for i := 0; i < N; i++ {
		A_list[i] = scanInt() // bufio.Scannerを呼び出す
	}
}

// scanInt scans int type.
func scanInt() (i int) {
	var err error
	sc.Scan()
	i, err = strconv.Atoi(sc.Text()) // int型にparse
	if err != nil {
		log.Fatal("Failed to input", err)
	}
	return
}

// ① Nの入力を受け付ける場合
func main() {
	var N int
	fmt.Scan(&N) // calling fmt.Scan
}

// ② 3*10^6回受け付ける場合
var sc = bufio.NewScanner(os.Stdin)

func main() {
    sc.Split(bufio.ScanWords) // split by word
	for i := 0; i < N; i++ {
		A_list[i] = scanInt() // calling bufio.Scanner
	}
}

// scanInt scans int type.
func scanInt() (i int) {
	var err error
	sc.Scan()
	i, err = strconv.Atoi(sc.Text()) // parse to int
	if err != nil {
		log.Fatal("Failed to input", err)
	}
	return
}