package main

import (
	"fmt"
)

func main() {
	var n, d int
	fmt.Scan(&n, &d)
	if n==d {
		fmt.Println("0")
		return
	}
	m := make([]bool, n)
	var j, cnt int
	for j == 0{
		for i := 0; i < n;{
			//fmt.Println("i", i)
			if m[i] {
				j = 1
				break
			}
			m[i] = true
			cnt++
			i = (i +d)%n
		}
	}
	fmt.Println(cnt-1)
}