#include <bits/stdc++.h>
using namespace std;
#define gc getchar_unlocked
#define fo(i,n) for(i=0;i<n;i++)
#define Fo(i,k,n) for(i=k;k<n?i<n:i>n;k<n?i+=1:i-=1)
#define ll long long
#define si(x)	scanf("%d",&x)
#define sl(x)	scanf("%lld",&x)
#define ss(s)	scanf("%s",s)
#define pi(x)	printf("%d\n",x)
#define pl(x)	printf("%lld\n",x)
#define ps(s)	printf("%s\n",s)
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define clr(x) memset(x, 0, sizeof(x))
#define sortall(x) sort(all(x))
#define tr(it, a) for(auto it = a.begin(); it != a.end(); it++)
#define PI 3.1415926535897932384626
typedef pair<int, int>	pii;
typedef pair<ll, ll>	pl;
typedef vector<int>		vi;
typedef vector<ll>		vl;
typedef vector<pii>		vpii;
typedef vector<pl>		vpl;
typedef vector<vi>		vvi;
typedef vector<vl>		vvl;
int mpow(int base, int exp); 
void ipgraph(int m);
void dfs(int u, int par);
const int mod = 1000000007;
const int N = 3e5, M = N;
//=======================

vi g[N];
int a[N];
void fac(ll no, vi &a){
	a.clear();
	while(no){
		a.pb(no%2);
		no /= 2;
	}
	while(a.size() < 60) a.pb(0);
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int i,n,j;
	ll A, B;
	cin >> A >> B;
	if(A == B){
		cout << 1 << endl;
		return 0;
	}
	int r = -1, k = -1, cur = -1;
	vi L, R;
	fac(A, L);
	fac(B, R);
	int p = 59;
	while(p>=0 and L[p] == R[p]){
		if(L[p]) L[p] = R[p] = 0, A -= 1LL<<p, B -= 1LL<<p;
		p--;
	}
	fo(i, 60){
		if(L[i] != R[i]) r = i;
		if(R[i]) k = cur, cur = i;
	}
	ll T = 1LL<<r;
	//[A, T-1]
	ll ans = (T-1) - A + 1;
	
	//[T, T+2^(k+1)-1]
	ans += 1LL<<(k+1);
	//[T+A, 2T-1]
	ans += 2*T-1 - (T+A) + 1;
	//If overlap
	ll x = (1LL<<(k+1)) - 1;
	if(A <=  x)
		ans -= x-A+1;
	cout << ans << endl;
	
	return 0;
}