#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int,int>;
const int N = 1e6+10;
int t,n,m,k,l,r,op,x,y;
int f[N];
unordered_set<int> st;
void solve(){
    cin>>x>>y;
    while(x){
        st.insert(x);
        x/=2;
    }
    while(y){
        if(st.find(y)!=st.end()){
            cout<<y;
            return;
        }
        y/=2;
    }

}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);  
    solve();
    return 0;
}