package main import ( "bufio" "fmt" "os" "strconv" ) func getNextString(scanner *bufio.Scanner) string { if !scanner.Scan() { panic("scan failed") } return scanner.Text() } func atoi(s string) int { x, _ := strconv.Atoi(s); return x } func getNextInt(scanner *bufio.Scanner) int { return atoi(getNextString(scanner)) } func atoi64(s string) int64 { x, _ := strconv.ParseInt(s, 10, 64); return x } func getNextInt64(scanner *bufio.Scanner) int64 { return atoi64(getNextString(scanner)) } func atof64(s string) float64 { x, _ := strconv.ParseFloat(s, 64); return x } func getNextFloat64(scanner *bufio.Scanner) float64 { return atof64(getNextString(scanner)) } func main() { fp := os.Stdin wfp := os.Stdout extra := 0 if os.Getenv("I") == "IronMan" { fp, _ = os.Open(os.Getenv("END_GAME")) extra = 100 } scanner := bufio.NewScanner(fp) scanner.Split(bufio.ScanWords) scanner.Buffer(make([]byte, 1000005), 1000005) writer := bufio.NewWriter(wfp) defer func() { r := recover() if r != nil { fmt.Fprintln(writer, r) } writer.Flush() }() solve(scanner, writer) for i := 0; i < extra; i++ { fmt.Fprintln(writer, "-----------------------------------") solve(scanner, writer) } } func solve(scanner *bufio.Scanner, writer *bufio.Writer) { SetMod(Mod998244353) n := getNextInt(scanner) k := getNextInt64(scanner) var sum Mint aa := make([]int, n) for i := 0; i < n; i++ { aa[i] = getNextInt(scanner) sum.AddAs(Mint(aa[i])) } sum.MulAs(Mint(2).Pow(Mint(k))) fmt.Fprintln(writer, sum) } // Mod constants. const ( Mod1000000007 = 1000000007 Mod998244353 = 998244353 ) var ( mod Mint fmod func(Mint) Mint ) // Mint treats the modular arithmetic type Mint int64 // SetMod sets the mod. It must be called first. func SetMod(newmod Mint) { switch newmod { case Mod1000000007: fmod = staticMod1000000007 case Mod998244353: fmod = staticMod998244353 default: mod = newmod fmod = dynamicMod } } func dynamicMod(m Mint) Mint { m %= mod if m < 0 { return m + mod } return m } func staticMod1000000007(m Mint) Mint { m %= Mod1000000007 if m < 0 { return m + Mod1000000007 } return m } func staticMod998244353(m Mint) Mint { m %= Mod998244353 if m < 0 { return m + Mod998244353 } return m } // Mod returns m % mod. func (m Mint) Mod() Mint { return fmod(m) } // Inv returns modular multiplicative inverse func (m Mint) Inv() Mint { return m.Pow(Mint(0).Sub(2)) } // Pow returns m^n func (m Mint) Pow(n Mint) Mint { p := Mint(1) for n > 0 { if n&1 == 1 { p.MulAs(m) } m.MulAs(m) n >>= 1 } return p } // Add returns m+x func (m Mint) Add(x Mint) Mint { return (m + x).Mod() } // Sub returns m-x func (m Mint) Sub(x Mint) Mint { return (m - x).Mod() } // Mul returns m*x func (m Mint) Mul(x Mint) Mint { return (m * x).Mod() } // Div returns m/x func (m Mint) Div(x Mint) Mint { return m.Mul(x.Inv()) } // AddAs assigns *m + x to *m and returns m func (m *Mint) AddAs(x Mint) *Mint { *m = m.Add(x) return m } // SubAs assigns *m - x to *m and returns m func (m *Mint) SubAs(x Mint) *Mint { *m = m.Sub(x) return m } // MulAs assigns *m * x to *m and returns m func (m *Mint) MulAs(x Mint) *Mint { *m = m.Mul(x) return m } // DivAs assigns *m / x to *m and returns m func (m *Mint) DivAs(x Mint) *Mint { *m = m.Div(x) return m }