#include <iostream>
#include <vector>

int n;
std::vector<int> Sn;
int count;
int main(){
    std::cin >> n;
    for(int i = 1;i <= n;i++){
        if( (i&n) == i ){
            Sn.push_back(i);
            count++;
        }
    }
    std::cout << Sn.at((count-1)/2) << std::endl;
}