#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#define llint long long

using namespace std;

llint n;

int main(void)
{
	cin >> n;
	assert(n >= 1 && n < (1LL<<60));
	
	vector<llint> vec;
	for(llint t = n; t; t = (t-1)&n) vec.push_back(t);
	sort(vec.begin(), vec.end());
	
	cout << vec[(int)vec.size()/2] << endl;
		
	return 0;
}