import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	
	public static int solve(int X, int Y){
		if(X == Y){ 
			return 0;
		}else if(Y == 0){
			// (X, 0) -> (X, X)
			return 1;
		}else if(X == 0){
			// (0, Y) -> (Y, 0)
			return 1 + solve(Y, 0);
		}else if(Math.abs(X) != Math.abs(Y)){
			return -1;
		}else{
			return solve(X + Y, X - Y);
		}
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int X = sc.nextInt();
		final int Y = sc.nextInt();
		
		System.out.println(solve(X, Y));
	}
}