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 final int INF = Integer.MAX_VALUE / 2 - 1;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int X = sc.nextInt();
		final int Y = sc.nextInt();
		
		int[][] DP = new int[100 + 1 + 100][100 + 1 + 100];
		for(int i = 0; i <= 200; i++){
			for(int j = 0; j <= 200; j++){
				DP[i][j] = (i == j) ? 0 : INF;
			}
		}
		
		while(true){
			boolean update = false;
			
			for(int i = 0; i <= 200; i++){
				for(int j = 0; j <= 200; j++){
					final int x = i - 100;
					final int y = j - 100;
					
					if(DP[i][j] > DP[i][j] + 1){
						DP[i][j] = DP[i][j] + 1; update = true;
					}
					if(j - i >= 0 && j + i <= 200 && DP[j - i][j + i] > DP[i][j] + 1){
						DP[j - i][j + i] = DP[i][j] + 1; update = true;
					}
				}
			}
			
			if(!update){ break; }
		}
		
		//System.out.println(solve(X, Y));
		System.out.println(DP[Y][X] == INF ? -1 : DP[Y][X]);
	}
}