#include <bits/stdc++.h>
using namespace std;
using ll = long long;

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    unsigned x, y;
    cin >> x >> y;
    if (__builtin_clz(x) > __builtin_clz(y)) {
        swap(x, y);
    }
    unsigned ans = 0;
    if (__builtin_clz(x) == __builtin_clz(y)) {
        ans = (1 << (31 - __builtin_clz(y))) - 1;
    } else {
        ans = y;
    }
    cout << ans << '\n';
    return 0;
}