ABC121 D – XOR World

//C++ language

#include<iostream>
using namespace std;

long long g(long long n){
    if(n<0) return 0;
    switch(n%4){
        case 0: return n;
        case 1: return 1;
        case 2: return n+1;
        case 3: return 0;
    }
}

int main(){
    long long A,B; cin>>A>>B;
    cout << (g(A-1)^g(B))<< "\n";
    return 0;
}