#include <bits/stdc++.h>
using namespace std;
#define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define ll long long
int main (){
    int N;
    cin >> N;
    vector<int> vec(0);
    rep2(i, 1, N+1){
        if ((i&N) == i){
            vec.push_back(i);
        }
    }
    int n = vec.size();
    cout << vec[(n-1)/2] << endl;
}