using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Text;
using static System.Math;
using static System.Linq.Enumerable;
using static Extentions;

public static class Program
{
    public static void Solve(IO io)
    {
        var (a, c) = io.Read<int, int>();
        io.Write(a ^ c);
    }

    public static void Main()
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput())
        {
            NewLine = "\n",
#if DEBUG
            AutoFlush = true,
#else
            AutoFlush = false,
#endif
        });
        Solve(new IO(Console.In, Console.Out));
        Console.Out.Flush();
    }
}

public static partial class Extentions
{
}

#region Library

// fuckin' slow
public class IO
{
    public delegate T Parser<out T>(string str);
    public delegate string Serializer<in T>(T value);

    private TextReader _tr;
    private TextWriter _tw;

    public IO(TextReader tr, TextWriter tw)
    {
        _tr = tr;
        _tw = tw;
    }

    public string ReadLine() => _tr.ReadLine();

    private string ReadWord()
    {
        var sb = new StringBuilder();
        Repeat(_tr.Read).TakeWhile(c => c != ' ' && c != '\n').ForEach(c => sb.Append((char)c));
        return sb.ToString();
    }

    public T Read<T>(Parser<T> parser = null) => parser != null
        ? parser(ReadWord()) : (T)Convert.ChangeType(ReadWord(), typeof(T));

    public (T1, T2) Read<T1, T2>(
        Parser<T1> parser1 = null, Parser<T2> parser2 = null)
        => (Read(parser1), Read(parser2));

    public (T1, T2, T3) Read<T1, T2, T3>(
        Parser<T1> parser1 = null, Parser<T2> parser2 = null,
        Parser<T3> parser3 = null)
        => (Read(parser1), Read(parser2), Read(parser3));

    public (T1, T2, T3, T4) Read<T1, T2, T3, T4>(
        Parser<T1> parser1 = null, Parser<T2> parser2 = null,
        Parser<T3> parser3 = null, Parser<T4> parser4 = null)
        => (Read(parser1), Read(parser2), Read(parser3), Read(parser4));

    public T[] Read<T>(int count, Parser<T> parser = null)
        => Repeat(() => Read(parser), count).ToArray();

    public (T1[], T2[]) Read<T1, T2>(int count,
        Parser<T1> parser1 = null, Parser<T2> parser2 = null)
        => Repeat(() => Read(parser1, parser2), count).ToArray().Unzip();

    public (T1[], T2[], T3[]) Read<T1, T2, T3>(int count,
        Parser<T1> parser1 = null, Parser<T2> parser2 = null,
        Parser<T3> parser3 = null)
        => Repeat(() => Read(parser1, parser2, parser3), count).ToArray().Unzip();

    public (T1[], T2[], T3[], T4[]) Read<T1, T2, T3, T4>(int count,
        Parser<T1> parser1 = null, Parser<T2> parser2 = null,
        Parser<T3> parser3 = null, Parser<T4> parser4 = null)
        => Repeat(() => Read(parser1, parser2, parser3, parser4), count).ToArray().Unzip();

    public void Write<T>(T value, Serializer<T> serializer = null)
    {
        _tw.Write(serializer != null ? serializer(value) : value.ToString());
        _tw.Write(' ');
    }

    public void Write<T1, T2>(T1 value1, T2 value2,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null)
    {
        Write(value1, serializer1);
        Write(value2, serializer2);
    }

    public void Write<T1, T2, T3>(T1 value1, T2 value2, T3 value3,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null,
        Serializer<T3> serializer3 = null)
    {
        Write(value1, serializer1);
        Write(value2, serializer2);
        Write(value3, serializer3);
    }

    public void Write<T1, T2, T3, T4>(T1 value1, T2 value2, T3 value3, T4 value4,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null,
        Serializer<T3> serializer3 = null, Serializer<T4> serializer4 = null)
    {
        Write(value1, serializer1);
        Write(value2, serializer2);
        Write(value3, serializer3);
        Write(value4, serializer4);
    }

    public void WriteLine<T>(T value, Serializer<T> serializer = null)
    {
        Write(value, serializer);
        _tw.WriteLine();
    }

    public void WriteLine<T1, T2>(T1 value1, T2 value2,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null)
    {
        Write(value1, value2, serializer1, serializer2);
        _tw.WriteLine();
    }

    public void WriteLine<T1, T2, T3>(T1 value1, T2 value2, T3 value3,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null,
        Serializer<T3> serializer3 = null)
    {
        Write(value1, value2, value3, serializer1, serializer2, serializer3);
        _tw.WriteLine();
    }

    public void WriteLine<T1, T2, T3, T4>(T1 value1, T2 value2, T3 value3, T4 value4,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null,
        Serializer<T3> serializer3 = null, Serializer<T4> serializer4 = null)
    {
        Write(value1, value2, value3, value4, serializer1, serializer2, serializer3, serializer4);
        _tw.WriteLine();
    }

    public void WriteLine<T>(IEnumerable<T> values, Serializer<T> serializer = null)
        => values.ForEach(v => WriteLine(v, serializer));

    public void WriteLine<T1, T2>(
        IEnumerable<T1> values1, IEnumerable<T2> values2,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null)
    {
        foreach (var (v1, v2) in values1.Zip(values2, ValueTuple.Create))
            WriteLine(v1, v2, serializer1, serializer2);
    }

    public void WriteLine<T1, T2, T3>(
        IEnumerable<T1> values1, IEnumerable<T2> values2,
        IEnumerable<T3> values3,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null,
        Serializer<T3> serializer3 = null)
    {
        foreach (var (v1, v2, v3) in values1.Zip(values2, values3, ValueTuple.Create))
            WriteLine(v1, v2, v3, serializer1, serializer2, serializer3);
    }

    public void WriteLine<T1, T2, T3, T4>(
        IEnumerable<T1> values1, IEnumerable<T2> values2,
        IEnumerable<T3> values3, IEnumerable<T4> values4,
        Serializer<T1> serializer1 = null, Serializer<T2> serializer2 = null,
        Serializer<T3> serializer3 = null, Serializer<T4> serializer4 = null)
    {
        foreach (var (v1, v2, v3, v4) in values1.Zip(values2, values3, values4, ValueTuple.Create))
            WriteLine(v1, v2, v3, v4, serializer1, serializer2, serializer3, serializer4);
    }
}

public static partial class Extentions
{
    public static void Assert(bool condition)
    {
        if (!condition) Environment.Exit(1);
    }

    public static string AsString(this IEnumerable<char> source) => new string(source.ToArray());

    public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
    {
        foreach (var item in source) action(item);
    }

    public static void ForEach<T, _>(this IEnumerable<T> source, Func<T, _> func)
    {
        foreach (var item in source) func(item);
    }

    public static void ForEach<T>(this IEnumerable<T> source, Action<T, int> action)
    {
        var i = 0;
        foreach (var item in source) action(item, i++);
    }

    public static void ForEach<T, _>(this IEnumerable<T> source, Func<T, int, _> func)
    {
        var i = 0;
        foreach (var item in source) func(item, i++);
    }

    public static void Repeat(Action action, int count)
    {
        for (var i = 0; i < count; i++) action();
    }

    public static void Repeat(Action<int> action, int count)
    {
        for (var i = 0; i < count; i++) action(i);
    }

    public static IEnumerable<T> Repeat<T>(Func<T> func)
    {
        for (var i = 0; ; i++) yield return func();
    }

    public static IEnumerable<T> Repeat<T>(Func<T> func, int count)
    {
        for (var i = 0; i < count; i++) yield return func();
    }

    public static IEnumerable<T> Repeat<T>(Func<int, T> func)
    {
        for (var i = 0; ; i++) yield return func(i);
    }

    public static IEnumerable<T> Repeat<T>(Func<int, T> func, int count)
    {
        for (var i = 0; i < count; i++) yield return func(i);
    }

    public static void Swap<T>(ref T x, ref T y)
    {
        var tmp = x; x = y; y = tmp;
    }

    public static (T1[], T2[]) Unzip<T1, T2>(
        this ICollection<(T1, T2)> source)
    {
        var ts1 = new T1[source.Count];
        var ts2 = new T2[source.Count];
        var i = 0;
        foreach (var (t1, t2) in source) { ts1[i] = t1; ts2[i] = t2; i++; }
        return (ts1, ts2);
    }

    public static (T1[], T2[], T3[]) Unzip<T1, T2, T3>(
        this ICollection<(T1, T2, T3)> source)
    {
        var ts1 = new T1[source.Count];
        var ts2 = new T2[source.Count];
        var ts3 = new T3[source.Count];
        var i = 0;
        foreach (var (t1, t2, t3) in source) { ts1[i] = t1; ts2[i] = t2; ts3[i] = t3; i++; }
        return (ts1, ts2, ts3);
    }

    public static (T1[], T2[], T3[], T4[]) Unzip<T1, T2, T3, T4>(
        this ICollection<(T1, T2, T3, T4)> source)
    {
        var ts1 = new T1[source.Count];
        var ts2 = new T2[source.Count];
        var ts3 = new T3[source.Count];
        var ts4 = new T4[source.Count];
        var i = 0;
        foreach (var (t1, t2, t3, t4) in source) { ts1[i] = t1; ts2[i] = t2; ts3[i] = t3; ts4[i] = t4; i++; }
        return (ts1, ts2, ts3, ts4);
    }

    public static IEnumerable<T> Zip<T1, T2, T3, T>(
        this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> thrid,
        Func<T1, T2, T3, T> resultSelector)
    {
        using (var e1 = first.GetEnumerator())
        using (var e2 = second.GetEnumerator())
        using (var e3 = thrid.GetEnumerator())
        {
            while (e1.MoveNext() && e2.MoveNext() && e3.MoveNext())
                yield return resultSelector(e1.Current, e2.Current, e3.Current);
        }
    }

    public static IEnumerable<T> Zip<T1, T2, T3, T4, T>(
        this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> thrid, IEnumerable<T4> fourth,
        Func<T1, T2, T3, T4, T> resultSelector)
    {
        using (var e1 = first.GetEnumerator())
        using (var e2 = second.GetEnumerator())
        using (var e3 = thrid.GetEnumerator())
        using (var e4 = fourth.GetEnumerator())
        {
            while (e1.MoveNext() && e2.MoveNext() && e3.MoveNext() && e4.MoveNext())
                yield return resultSelector(e1.Current, e2.Current, e3.Current, e4.Current);
        }
    }
}

#endregion