2023.3.19 AM 08:50 by CBJ

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//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;
}
