#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int get(int n){
	int ret=  1;
	while(ret*2 <= n){
		ret *= 2;
	}
	return ret;
}

int main(){
	
	int A,B;
	cin>>A>>B;
	
	int X = get(A),Y=  get(B);
	if(X!=Y){
		cout<<min(A,B)<<endl;
	}
	else{
		cout<<X-1<<endl;
	}
	
	return 0;
}