#include <bits/stdc++.h>
using namespace std;
using ll = long long;

ll f(int n){
  ll pow = 1;
  while(n>0){
    pow *= 2;
    n--;
  }
  return pow;
}

int main(){
  ll m; cin >> m;
  int ans = 0;
  for(int i = 0; i <= 60; i++){
    if(f(i)>m){
      ans = i;
      break;
    }
  }
  cout << f(ans-1) << endl;
  return 0;
}