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

int main(){

  int A, B;
  cin >> A >> B;
  assert(1 <= A && A <= (int)1e9);
  assert(1 <= B && B <= (int)1e9);

  if(A < B)swap(A, B);
  
  int bit = 1;
  while(bit * 2 <= A)bit *= 2;
  cout << min(bit - 1, B) << endl;
}