import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

alias sread = () => readln.chomp();
ulong bignum = 1_000_000_007;
alias SugarWater = Tuple!(long, "swater", long, "sugar");

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void main()
{
    long a, b;
    scan(a, b);
    if (a % 2)
        calcans(a, b, a);
    else
    {
        if (b - a < 3)
        {
            long ans = a;
            foreach (e; a .. b)
                ans ^= e + 1;

            ans.writeln();
        }
        else
            calcans(a + 3, b, 0);
    }
}

void calcans(long a, long b, long c)
{
    long skip = (b - a) / 4;
        skip *= 4;
        long start = a + skip, ans = c;
        foreach (e; start .. b)
            ans ^= e + 1;

        ans.writeln();
}