#ifndef __MATH_UTIL_H__
#define __MATH_UTIL_H__

/* updated: 2020-03-17 */

#include <cstdint>
#include <cassert>
#include <vector>

int64_t strictMod(int64_t a, int64_t b);
int64_t strictDiv(int64_t a, int64_t b);

template <class T>
T power(T base, uint64_t exp);

/* 累乗 O(logN) */
template <class T>
T power(T base, uint64_t exp) {
	T product = T(1);
	while (exp > 0) {
		if (exp & 1) {
			product *= base;
		}
		base *= base;
		exp >>= 1;
	}
	return product;
}

int digits(uint64_t num, uint64_t radix = 10);
std::vector<uint64_t> radixEncoding(uint64_t num, uint64_t radix, int length = -1);
uint64_t radixDecoding(const std::vector<uint64_t>& arr, uint64_t radix);

#endif

#ifdef ONLY_MY_ENVIR
#include "MathUtil.h"
#endif

/* 丸め方向を揃えた剰余 */
int64_t strictMod(int64_t a, int64_t b) {
	assert(b > 0);
	int64_t mod = a % b;
	if (mod < 0) mod += b;
	return mod;
}

/* 丸め方向を揃えた除算 */
int64_t strictDiv(int64_t a, int64_t b) {
	assert(b > 0);
	return (a - strictMod(a, b)) / b;
}

/* 整数 num を radix 進法で表した時の桁数を返す (num == 0 のときは 0 を返す) */
int digits(uint64_t num, uint64_t radix) {
	int count = 0;
	while (num > 0) {
		num /= radix;
		++count;
	}
	return count;
}

/* 基数変換 / uint を radix 進数に変換する */
/* 戻り値は各桁の値を格納した配列(1の位から格納) */
/* 値 0 に対しては空列を返す */
/* length に正の数を指定すると戻り値を固定長にする */
std::vector<uint64_t> radixEncoding(uint64_t num, uint64_t radix, int length) {
	assert(radix >= 2);

	std::vector<uint64_t> arr;
	while (num > 0) {
		arr.push_back(num % radix);
		num /= radix;
	}

	if (length >= 0) {
		arr.resize(length, uint64_t());
	}

	return arr;
}

/* 基数変換 / radix 進数 を uint に変換する */
/* 引数は各桁の値を格納した配列(1の位から格納) */
uint64_t radixDecoding(const std::vector<uint64_t>& arr, uint64_t radix) {
	assert(radix >= 2);

	uint64_t num = 0;
	uint64_t base = 1;
	for (int i = 0; i < arr.size(); ++i) {
		num += arr[i] * base;
		base *= radix;
	}
	return num;
}
#define _CRT_SECURE_NO_WARNINGS
#define _SCL_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <utility>
#include <algorithm>
#include <functional>
#include <cmath>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <iomanip>
#include <sstream>
#include <bitset>
#include <limits>
#include <numeric>
#include <valarray>
#include <fstream>
#include <array>
#include <random>
#include <unordered_set>
#include <unordered_map>

using namespace std;
using uint = uint32_t;
using LL = int64_t;
using ULL = uint64_t;
using PP = pair<LL, LL>;
template <typename T> using PriorityQ = priority_queue<T, vector<T>, greater<T> >;
#define REP(i, a, n) for(LL i = (a), i##_max_ = (n); i < i##_max_; ++i)
#define REM(i, a, n) for(LL i = (LL)(n) - 1, i##_min_ = (a); i >= i##_min_; --i)
#define FLOAT fixed << setprecision(16)
#define SPEEDUP { cin.tie(NULL); ios::sync_with_stdio(false); }
const int INF = 0x3FFFFFFF;
const LL INFLL = 0x3FFFFFFF3FFFFFFF;
const double INFD = 1.0e+308;
const double EPS = 1.0e-9;

void YesNo(bool b) { cout << (b ? "Yes" : "No") << endl; }
void YESNO(bool b) { cout << (b ? "YES" : "NO") << endl; }
template <class T, class U> istream& operator>>(istream& ist, pair<T, U>& right) { return ist >> right.first >> right.second; }
template <class T, class U> ostream& operator<<(ostream& ost, const pair<T, U>& right) { return ost << right.first << ' ' << right.second; }
template <class T, class TCompatible, size_t N> void Fill(T(&dest)[N], const TCompatible& val) { fill(dest, dest + N, val); }
template <class T, class TCompatible, size_t M, size_t N> void Fill(T(&dest)[M][N], const TCompatible& val) { for (int i = 0; i < M; ++i) Fill(dest[i], val); }
template <class T> T Next() { T buf; cin >> buf; return buf; }
istream& Ignore(istream& ist) { string s; ist >> s; return ist; }
bool Inside(int i, int j, int h, int w) { return i >= 0 && i < h && j >= 0 && j < w; }

#ifdef ONLY_MY_ENVIR
#include "IntMod.h"
#include "Accumulator.h"
#include "Algebraic.h"
#include "BinaryMatrix.h"
#include "BinaryTree.h"
#include "Bipartite.h"
#include "BIT.h"
#include "Compressor.h"
#include "Decompositions.h"
#include "DynamicMod.h"
#include "Factorization.h"
#include "FFT.h"
#include "FlowSolver.h"
#include "Graph.h"
#include "GraphUtil.h"
#include "LazySegmentTree.h"
#include "LIS.h"
#include "Math.h"
#include "MathUtil.h"
#include "Matrix.h"
#include "MinCostFlowSolver.h"
#include "MinMax.h"
#include "Numbers.h"
#include "Optimize.h"
#include "Permutation.h"
#include "Polynomial.h"
#include "Position.h"
#include "Range.h"
#include "Rational.h"
#include "SegmentTree.h"
#include "SegmentTree2D.h"
#include "Sets.h"
#include "Shortest.h"
#include "SlidingWindow.h"
#include "SpanningTree.h"
#include "StringSearching.h"
#include "SuffixArray.h"
#include "Tree.h"
#include "UnionFind.h"
#include "VectorUtil.h"
#endif

#ifdef __GNUC__
typedef __int128 LLL;
istream& operator>>(istream& ist, __int128& val) { LL tmp; ist >> tmp; val = tmp; return ist; }
ostream& operator<<(ostream& ost, __int128 val) { LL tmp = val; ost << tmp; return ost; }
#endif

LL full(LL B) {
	int P = digits(B, 2);
	B ^= 1LL << (P - 1);
	int Q = digits(B, 2);
	B = (1LL << Q) - 1;
	return B | (1LL << (P - 1));
}

LL sub(LL A, LL B) {
	if (A == B) return 1;
	int P = digits(A, 2);
	int Q = digits(B, 2);
	if (P == Q) {
		LL K = 1LL << (P - 1);
		return sub(A ^ K, B ^ K);
	} else {
		LL K = 1LL << (Q - 1);
		LL BB = full(B);
		return (K - A) + (K + A > BB ? (K - A) + (BB + 1 - K) : K);
	}
}

int main() {
	LL A, B;
	cin >> A >> B;
	cout << sub(A, B) << endl;
	return 0;
}




Measured memory_bytes: 256