#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define rep(i,n) for (int i=0;i<(int)(n);i++)
#define codefor int test;scanf("%d",&test);while(test--)
#define INT(...) int __VA_ARGS__;in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;in(__VA_ARGS__)
#define yes(ans) if(ans)printf("yes\n");else printf("no\n")
#define Yes(ans) if(ans)printf("Yes\n");else printf("No\n")
#define YES(ans) if(ans)printf("YES\n");else printf("NO\n")
#define vector1d(type,name,...) vector<type>name(__VA_ARGS__)
#define vector2d(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__))
#define umap unordered_map
#define uset unordered_set
using namespace std;
using ll = long long;
const int MOD=1000000007;
//入力系
void scan(int& a){scanf("%d",&a);}
void scan(long long& a){scanf("%lld",&a);}
template<class T> void scan(T& a){cin>>a;}
template<class T> void scan(vector<T>& vec){for(auto&& it:vec)scan(it);}
void in(){}
template <class Head, class... Tail> void in(Head& head, Tail&... tail){scan(head);in(tail...);}
//出力系
void print(const int& a){printf("%d",a);}
void print(const long long& a){printf("%lld",a);}
void print(const double& a){printf("%.15lf",a);}
template<class T> void print(const T& a){cout<<a;}
template<class T> void print(const vector<T>& vec){if(vec.empty())return;print(vec[0]);for(auto it=vec.begin();++it!= vec.end();){putchar(' ');print(*it);}}
void out(){putchar('\n');}
template<class T> void out(const T& t){print(t);putchar('\n');}
template <class Head, class... Tail> void out(const Head& head,const Tail&... tail){print(head);putchar(' ');out(tail...);}
//デバッグ系
template<class T> void dprint(const T& a){cerr<<a;}
template<class T> void dprint(const vector<T>& vec){if(vec.empty())return;cerr<<vec[0];for(auto it=vec.begin();++it!= vec.end();){cerr<<" "<<*it;}}
void debug(){cerr<<endl;}
template<class T> void debug(const T& t){dprint(t);cerr<<endl;}
template <class Head, class... Tail> void debug(const Head& head, const Tail&... tail){dprint(head);cerr<<" ";debug(tail...);}
ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; }
ll modpow(ll a, ll b, ll p){ ll ans = 1; while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
ll updivide(ll a,ll b){if(a%b==0) return a/b;else return (a/b)+1;}

//[A,B]の範囲にある整数の中でkの余剰をとったものがx以上となるものの数を求める
long long int RangeMod(long long A,long long B,long long k,long long x){
    long long left,right,left_mod,right_mod,ans;
    left=A/k;
    left_mod=A%k;
    right=B/k;
    right_mod=B%k;
    if(left==right){
        if(left_mod>=x&&right_mod>=x)ans=right_mod-left_mod+1;
        else if(left_mod<x&&right_mod>=x)ans=right_mod-x+1;
        else if(left_mod<x&&right_mod<x)ans=0;
    }else{
        if(k<x)ans=0;
        else{
            ans=(right-left-1)*(k-x);
            if(left_mod<x)ans+=k-x;
            else if(left_mod!=0)ans+=k-left_mod;
            if(right_mod>=x)ans+=right_mod-x+1;
        }
    }
    return ans;
}

int main(){
    ll d=1;
    LL(A,B);
    vector<ll> ans(62,0);
    for(int i=0;i<62;i++){
        d*=2;
        ans[i]=RangeMod(A,B,d,d/2)%2;
    }
    d=1;
    ll answer=0;
    for(int i=0;i<62;i++){
        answer+=d*ans[i];
        d*=2;
    }
    out(answer);
}


Measured memory_bytes: 3796