using System;
using System.Diagnostics;
using System.IO;

namespace AtCoder.ABC121 {
    class D {
        static void Main() => CustomMain();

        static void Solve() {
            long a, b;
            ReadMulti(out a, out b);

            long ans = 0;

            var aa = 4 - a % 4;
            if (aa == 4) aa = 0;
            for (long i = a; i < a + aa; i++) {
                ans ^= i;
                if (i == b) {
                    WriteAnswer(ans);
                    return;
                }
            }

            var bb = (b % 4);
            for (long i = b - bb; i <= b; i++) {
                ans ^= i;
            }

            WriteAnswer(ans);
        }

        class UnionFind {
            public int[] Data;

            public UnionFind(int n) {
                Data = new int[n];
                for (int i = 0; i < n; i++) {
                    Data[i] = -1;
                }
            }

            public int Root(int a) {
                if (Data[a] < 0) return a;
                return Data[a] = Root(Data[a]);
            }

            public bool Connect(int a, int b) {
                a = Root(a);
                b = Root(b);
                if (a == b) return false;

                if (Data[a] > Data[b]) {
                    var t = a;
                    a = b;
                    b = t;
                }

                Data[a] += Data[b];
                Data[b] = a;
                return true;
            }
        }

        static void CustomMain() {
#if DEBUG
            // ファイルからテストケースを読み込む
            global::Common.ChangeStdIn();
            // 時間計測
            var stopwatch = new Stopwatch();
            stopwatch.Start();
#endif
            // 出力高速化
            var streamWriter = new StreamWriter(Console.OpenStandardOutput()) {AutoFlush = false};
            Console.SetOut(streamWriter);
            // 回答
            Solve();
#if DEBUG
            stopwatch.Stop();
            Console.WriteLine(stopwatch.Elapsed);
#endif
            Console.Out.Flush();
        }

        static string ReadString() => Console.ReadLine().Trim();
        static int ReadInt() => int.Parse(ReadString());
        static long ReadLong() => long.Parse(ReadString());
        static float ReadFloat() => float.Parse(ReadString());
        static double ReadDouble => double.Parse(ReadString());

        static string[] ReadStringArray() => ReadString().Split(' ');
        static int[] ReadIntArray() => Array.ConvertAll(ReadString().Split(' '), int.Parse);
        static long[] ReadLongArray() => Array.ConvertAll(ReadString().Split(' '), long.Parse);
        static float[] ReadFloatArray() => Array.ConvertAll(ReadString().Split(' '), float.Parse);
        static double[] ReadDoubleArray() => Array.ConvertAll(ReadString().Split(' '), double.Parse);

        static T TypeConversion<T>(string s) {
            if (typeof(T) == typeof(int)) {
                return (T) Convert.ChangeType(int.Parse(s), typeof(T));
            } else if (typeof(T) == typeof(long)) {
                return (T) Convert.ChangeType(long.Parse(s), typeof(T));
            } else if (typeof(T) == typeof(double)) {
                return (T) Convert.ChangeType(double.Parse(s), typeof(T));
            } else {
                return (T) Convert.ChangeType(s, typeof(T));
            }
        }

        static void ReadMulti<T, U>(out T a, out U b) {
            var str = ReadStringArray();
            a = TypeConversion<T>(str[0]);
            b = TypeConversion<U>(str[1]);
        }

        static void ReadMulti<T, U, V>(out T a, out U b, out V c) {
            var str = ReadStringArray();
            a = TypeConversion<T>(str[0]);
            b = TypeConversion<U>(str[1]);
            c = TypeConversion<V>(str[2]);
        }

        static void WriteAnswer(object ans) => Console.WriteLine(ans);

        static bool IsOdd(long num) {
            return (num & 1) == 1;
        }

        static bool IsEven(long num) {
            return (num & 1) == 0;
        }
    }
}

Measured memory_bytes: 11348