import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StringReader;
import java.util.StringTokenizer;

public class Main  implements Runnable {
	long M = 1000000007;
	long[] fac = new long[300001];
	long[] ifac = new long[300001];
    public static void main(String[] args) {

        new Thread(null, new Main(), "", 16 * 1024 * 1024).start();

    }

    public void run() {
    	FastScanner sc = new FastScanner(System.in);
		//long n = Long.parseLong(sc.next());
    	//int[] ar = new int[3];
    	//ar[0]=Integer.parseInt(sc.next());
    	//ar[1]=Integer.parseInt(sc.next());
    	//ar[2]=Integer.parseInt(sc.next());
    	//Arrays.parallelSort(ar);
		//int a = Integer.parseInt(sc.next());
		long a = Long.parseLong(sc.next());
		long b = Long.parseLong(sc.next());
		//int l = Integer.parseInt(sc.next());
		//long a = Long.parseLong(sc.next());
		//String s = sc.next();
		//int k = Integer.parseInt(sc.next());
		//int m = Integer.parseInt(sc.next());
		//int x2000 = Integer.parseInt(sc.next());
		//int t = Integer.parseInt(sc.next());
		//int k = 0;
		//int k = Integer.parseInt(sc.next());
		//String str = sc.next();
		//char c[] = str.toCharArray();
		//char a[][] = new char[n];
		//int atmp[] = new int[h];
		//int max= 0;
		//int blackar[][] = new int[h*w][2];
		//int p=0;
		//ArrayList<Str_4> lists = new ArrayList<Str_4>();
		//lists = new ArrayList;
		PrintWriter out = new PrintWriter(System.out);
		long ans =0;
		long[] pow2 = new long[44];
		pow2[0] = 1;
		if(a>0)
		{
			a--;
		}
		ans += (((a+1l)/2l)%2l);
		for(int i = 1; i < 44; i++)
		{
			pow2[i] = pow2[i-1]*2l;
		}
		for(int i = 43; i >= 1; i--)
		{
			if(pow2[i] <= a)
			{
				a -= pow2[i];
				if(a%2 == 0)
				{
					ans += pow2[i];
				}
			}
		}
		long ans2=0;
		ans2 += (((b+1l)/2l)%2l);
		for(int i = 43; i >= 1; i--)
		{
			if(pow2[i] <= b)
			{
				b -= pow2[i];
				if(b%2 == 0)
				{
					ans2 += pow2[i];
				}
			}
		}
		ans = ans^ans2;
		out.println(ans);
		out.flush();
	}
    boolean ok (String s)
    {
    	if (
    			s.matches(".*agc.*")  || 
    			s.matches("a.gc") || 
    			s.matches("ag.c") || 
    			s.matches(".*acg.*")  ||
    			s.matches(".*gac.*") 
    		)
    	{
    		return false;
    	}
    	else
    	{
    		return true;
    	}
    }
    long mpow(long x, long n){
        long ans = 1;
        while(n != 0){
            if(n%2==1) ans = ans*x % M;
            x = x*x % M;
            n = n >> 1;
        }
        return ans;
    }

    long comb(long a, long b){ //aCbをmod計算
        if(a == 0 && b == 0)return 1;
        if(a < b || a < 0)return 0;
        long tmp = ifac[(int)(a-b)]* ifac[(int)b] % M;
        return tmp * fac[(int)a] % M;
    }
    static class FastScanner {
        private BufferedReader reader = null;
        private StringTokenizer tokenizer = null;
        public FastScanner(String in) {
        	StringReader sr = new StringReader(in);
            reader = new BufferedReader(new BufferedReader(sr));
            tokenizer = null;
        }
        public FastScanner(InputStream in) {
            reader = new BufferedReader(new InputStreamReader(in));
            tokenizer = null;
        }

        public String next() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public String nextLine() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    return reader.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }

            return tokenizer.nextToken("\n");
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public long nextInt() {
            return Integer.parseInt(next());
        }

    }


}
class Str_4 {
	String s;
	int n;
	Str_4(String ts, int tn)
	{
		s = ts;
		n = tn;
	}
}

Measured memory_bytes: 25300