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public static void main(String[] args)throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer in = new StringTokenizer(br.readLine());
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

        long x = Long.parseLong(in.nextToken());
        long y = Long.parseLong(in.nextToken());

        if(x==y){
            out.println(0);
        }else if(y==0){
            // 第二个数为0，1步操作即可满足条件
            out.println(1);
        }else if(x==0){
            // 第一个数为0，2步操作即可满足条件
            out.println(2);
        }else if(x+y==0){
             // 两数互为相反数（y = -x），3步操作满足条件
            out.println(3);
        }else{
            out.println(-1);
        }

        out.flush();
        out.close();
        br.close();
   }