#include <bits/stdc++.h>

using namespace std;
#define FOR(i,n) for(int i = 0; i < (n); i++)
#define sz(c) ((int)c.size())
#define ten(n) ((int)1e##n)
using ll = long long;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

template<typename ...> static inline int getchar_unlocked(void) { return getchar(); }
template<typename ...> static inline void putchar_unlocked(int c) { putchar(c); }
#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)
void reader(int& x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = x * 10 + k - '0'; }if (m) x = -x; }
void reader(ll& x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = x * 10 + k - '0'; }if (m) x = -x; }
int reader(char c[]) { int i, s = 0; for (;;) { mygc(i); if (i != ' '&&i != '\n'&&i != '\r'&&i != '\t'&&i != EOF) break; }c[s++] = i; for (;;) { mygc(i); if (i == ' ' || i == '\n' || i == '\r' || i == '\t' || i == EOF) break; c[s++] = i; }c[s] = '\0'; return s; }
int reader(string& c) { int i; for (;;) { mygc(i); if (i != ' '&&i != '\n'&&i != '\r'&&i != '\t'&&i != EOF) break; }c.push_back(i); for (;;) { mygc(i); if (i == ' ' || i == '\n' || i == '\r' || i == '\t' || i == EOF) break; c.push_back(i); }; return sz(c); }
template <class T, class S> void reader(T& x, S& y) { reader(x); reader(y); }
template <class T, class S, class U> void reader(T& x, S& y, U& z) { reader(x); reader(y); reader(z); }
template <class T, class S, class U, class V> void reader(T& x, S& y, U& z, V & w) { reader(x); reader(y); reader(z); reader(w); }
void writer(int x, char c) { int s = 0, m = 0; char f[10]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(ll x, char c) { int s = 0, m = 0; char f[20]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(const char c[]) { int i; for (i = 0; c[i] != '\0'; i++)mypc(c[i]); }
void writer(const string& x, char c) { int i; for (i = 0; x[i] != '\0'; i++)mypc(x[i]); mypc(c); }
void writer(const char x[], char c) { int i; for (i = 0; x[i] != '\0'; i++)mypc(x[i]); mypc(c); }
template<class T> void writerLn(T x) { writer(x, '\n'); }
template<class T, class S> void writerLn(T x, S y) { writer(x, ' '); writer(y, '\n'); }
template<class T, class S, class U> void writerLn(T x, S y, U z) { writer(x, ' '); writer(y, ' '); writer(z, '\n'); }
template<class T> void writerArr(T x[], int n) { if (!n) { mypc('\n'); return; }FOR(i, n - 1)writer(x[i], ' '); writer(x[n - 1], '\n'); }
template<class T> void writerArr(vector<T>& x) { writerArr(x.data(), (int)x.size()); }

template<class T> void chmin(T& a, const T& b) { if (a > b) a = b; }
template<class T> void chmax(T& a, const T& b) { if (a < b) a = b; }

template<class T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
ll mod_pow(ll a, ll n, ll mod) {
	ll ret = 1;
	ll p = a % mod;
	while (n) {
		if (n & 1) ret = ret * p % mod;
		p = p * p % mod;
		n >>= 1;
	}
	return ret;
}
template<class T> T extgcd(T a, T b, T& x, T& y) { for (T u = y = 1, v = x = 0; a;) { T q = b / a; swap(x -= q * u, u); swap(y -= q * v, v); swap(b -= q * a, a); } return b; }
template<class T> T mod_inv(T a, T m) { T x, y; extgcd(a, m, x, y); return (m + x % m) % m; }
template<class T> T CRT(T m1, T r1, T m2, T r2) { T a1, a2; extgcd(m1, m2, a1, a2); T ret = (m1*a1*r2 + m2*a2*r1) % (m1*m2); return ret < 0 ? ret + m1 * m2 : ret; }

const int MOD = ten(9) + 7;

const int C = 1<<10;
bool dp[C + 1];

vector<int> test(int a, int b) {
	if (b >= C) {
		exit(-1);
	}
	memset(dp, 0, sizeof(dp));
	dp[0] = 1;
	for (int i = a; i <= b; i++) {
		FOR(j, C) if (dp[j]) {
			dp[i | j] = true;
		}
	}
	dp[0] = false;
	vector<int> ans;
	FOR(i, C) {
		if (!dp[i] && dp[i + 1]) {
			ans.push_back(i + 1);
		} else if (dp[i] && !dp[i + 1]) {
			ans.push_back(i);
		}
	}
	if (sz(ans) % 2 != 0) {
		cout << "?" << endl;
	}
	//printf("a=%d,b=%d : ", a, b);
	//FOR(i, sz(ans) / 2) {
	//	printf("[%d,%d) ", ans[i * 2], ans[i * 2 + 1]);
	//}
	//puts("");
	return ans;
}

string bin(int x) {
	string ret;
	FOR(j, 11) {
		if (x & (1 << j)) ret.push_back('1');
		else ret.push_back('0');
	}
	reverse(ret.begin(), ret.end());
	return ret;
}

ll solve(ll a, ll b) {
	if (a == b) return 1;
	for (int j = 60; j >= 0; j--) {
		int bt = ((a >> j) ^ (b >> j)) & 1;
		if (bt) {
			ll l1 = a;
			ll r2 = (1LL << (j + 1)) - 1;

			int k = j - 1;
			for (; k >= 0; k--) {
				if ((b >> k) & 1) {
					break;
				}
			}

			ll r1 = (1LL << j);
			r1 += (1LL << (k + 1)) - 1;

			ll l2 = a | (1LL << j);


			ll ans = 0;
			if (l2 <= r1) {
				ans = (r2 - l1) + 1;
			} else {
				ans = (r2 - l2) + 1 + (r1 - l1) + 1;
			}
			return ans;
		} else {
			a &= ~(1LL << j);
			b &= ~(1LL << j);
		}
	}
}

void test() {

}

int main() {

	//for (int i = 141; i < 1000; i++) {
	//	vector<int> aa;
	//	for (int j = i; j < 1000; j++) {
	//		auto bb = test(i, j);
	//		if (aa != bb) {
	//			aa = bb;
	//			auto e = bin(i), f = bin(j);
	//			printf("a=%s,b=%s : ", e.c_str(), f.c_str());
	//			FOR(i, sz(aa) / 2) {
	//				auto g = bin(aa[i * 2]), h = bin(aa[i * 2 + 1]);
	//				printf("[%s,%s) ", g.c_str(), h.c_str());
	//			}
	//			puts("");
	//		}

	//	}
	//}

	//auto debug = test(a, b);
	//auto debug_ans = 0;
	//FOR(i, sz(debug) / 2) {
	//	debug_ans += debug[i * 2 + 1] - debug[i * 2] + 1;
	//}

	//ll ans = solve(a, b);
	//if (debug_ans != ans) {
	//	puts("?");
	//}

	ll a, b; reader(a, b);
	ll ans = solve(a, b);
	writerLn(ans);

	return 0;
}

Measured memory_bytes: 256