package main import ( "bufio" "fmt" "math" "os" "strconv" ) const INFINITY = math.MaxInt64/2 - 1 func exec(stdin *Stdin, stdout *Stdout) { n := stdin.ReadInt() p := stdin.ReadFloat64() e := 0.0 for i := 2; i <= n; i++ { c := f(i) e += math.Pow(1-p, float64(c-2)) } stdout.Println(e) } func f(x int) int { d := map[int]int{} y := 2 for x > 1 { for x%y == 0 { if _, ok := d[y]; ok { d[y]++ } else { d[y] = 1 } x /= y } y++ } e := 1 for _, v := range d { e *= v + 1 } return e } func main() { stdout := NewStdout() defer stdout.Flush() exec(NewStdin(bufio.ScanWords), stdout) } type Stdin struct { stdin *bufio.Scanner } func NewStdin(split bufio.SplitFunc) *Stdin { s := Stdin{bufio.NewScanner(os.Stdin)} s.stdin.Split(split) s.stdin.Buffer(make([]byte, bufio.MaxScanTokenSize), INFINITY) return &s } func (s *Stdin) Read() string { s.stdin.Scan() return s.stdin.Text() } func (s *Stdin) ReadInt() int { n, _ := strconv.Atoi(s.Read()) return n } func (s *Stdin) ReadFloat64() float64 { n, _ := strconv.ParseFloat(s.Read(), 64) return n } type Stdout struct { stdout *bufio.Writer } func NewStdout() *Stdout { return &Stdout{bufio.NewWriter(os.Stdout)} } func (s *Stdout) Flush() { s.stdout.Flush() } func (s *Stdout) Println(a ...interface{}) { fmt.Fprintln(s.stdout, a...) } func Min(a int, b ...int) int { for _, v := range b { if v < a { a = v } } return a } func Max(a int, b ...int) int { for _, v := range b { if a < v { a = v } } return a } func Abs(x int) int { if x > 0 { return x } else { return x * -1 } } func Pow(x, y int) int { z := 1 for y > 0 { if y%2 == 0 { x *= x y /= 2 } else { z *= x y -= 1 } } return z } func CreateMatrix(x, y int) [][]int { matrix := make([][]int, x) for i := 0; i < x; i++ { matrix[i] = make([]int, y) } return matrix }