Go: package main

import "fmt"

func main() {
	var n int
	fmt.Scanln(&n)
	l, r, max := 0, 63, 0
	for l <= r {
		m := (l + r) / 2
		pow2 := 1 << uint(m)
		if pow2 <= n {
			l = m + 1
			if pow2 > max {
				max = pow2
			}
		} else {
			r = m - 1
		}
	}
	fmt.Println(max)
}

C++: #include<stdio.h>
#include<stdlib.h>
#include<algorithm>
using namespace std;
int main(void)
{
	int x,n;
	scanf("%d",&n);
	x=2;
	while(n>=x)	x=x*2;
	printf("%d\n",x/2);
	return 0;
}

C++: #include <iostream>
//#include <iomanip>
//#include <string>
//#include <vector>
//#include <algorithm>
//#include <utility>
//#include <set>
//#include <map>
//#include <queue>
//#include <deque>
//#include <bitset>
//#include <math.h>
using namespace std ;
using ll = long long ;
//using ld = long double ;
//using vll = vector<ll> ;
//using vvll = vector<vll> ;
//using vc = vector<char> ;
//using vvc = vector<vc> ;
//using vb = vector<bool> ;
//using vvb = vector<vb> ;
//using pll = pair<ll,ll> ;

//ll mod = 1000000007 ;
//long double pie = acos(-1) ;

//void yorn(bool a){if(a) cout << "Yes" << endl ; else cout << "No" << endl ;}
//void YorN(bool a){if(a) cout << "YES" << endl ; else cout << "NO" << endl ;}
//ll gcd(long long a,long long b){if(b==0) return a ; return gcd(b,a%b) ;}
//ll lcm(long long a,long long b){return a/gcd(a,b)*b ;}
//ll sa(long long a,long long b){if(a>b) return a-b ; return b-a ;}
//void mysort(vector<long long> &a){sort(a.begin(),a.end()) ;}
//void myrev(vector<long long> &a){reverse(a.begin(),a.end()) ;}

int main(){
	ll n ; cin >> n ;
	ll cnt = 0 ;
	while(n>0){
		cnt++ ;
		n /= 2 ;
	}
	ll ans = 1 ;
	for(int i=0;i<cnt-1;i++) ans *= 2 ;
	cout << ans << endl ;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <set>
using namespace std;
typedef long long int ll;

int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	int n; cin >> n;
	int cnt=0;
	while(n){
		cnt++;
		n/=2;
	}
	cout << (1<<(cnt-1)) << endl;
}

C++: #include <iostream>
using namespace std;
int main(){
    int n;cin>>n;
    int nw = 1;
    while(n >= nw)nw*=2;
    cout << nw/2 << endl;
}

C++: #include<stdio.h>
int main(void) {
	int N,a,b=2;
	scanf("%d", &N);
	while (1) {
		if (b <= N && N < b * 2) {
			break;
		}
		b = b*2;
	}
	printf("%d\n", b);
	return 0;
}

C++: #include<iostream>
using namespace std;
int main(){
    int a,b=1;
    cin >>a;
    while(b*2<=a){
        b*=2;
        
    }
    cout<<b<<endl;;
}

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


signed main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
 
    int n;
    cin>>n;
    int ans = 1;
    while(n>=2){
        ans*=2;
        n/=2;
    }
    cout << ans<< endl;
    
}

C++: #include <bits/stdc++.h>
using namespace std;

int main(){
    int N;
    cin >> N;
    int r = 2;
    while(1){
        if(r > N){
            cout << r/2 << endl;
            break;
        }
        r *= 2;
    }
}

C++: #include <iostream>
using namespace std;

int main(){

	int N ; 
	int i ;
	int outputNum = 1 ;
	
	cin >> N ;

	//10の6乗は100万。2の20乗は100万より少し大きい
	for( i =0 ; i <= 20; ){

		if( N < outputNum ){
		cout << outputNum / 2 << endl ;
		break;  //For文から抜ける
		}else{ //何もしない
		}

	outputNum = outputNum * 2 ;
	i = i + 1;
	}
	

}

C++: #include<iostream>
using namespace std;


int main()
{
	int n;
	cin >> n;
	int a = 1;
	while (a <= n)
		a <<= 1;
	cout << a/2 << endl;
}

C++: #include <iostream>
using namespace std;
int main(){
    int sample,ans=1;
    cin >> sample;
    while(ans<=sample){
        ans=ans*2;
    }
    cout << ans/2 << endl;
}

C++: #include <iostream>
using namespace std;
int main(){
    
    int N , X ;
    cin >> N ;
    
        X = 1 ;
    
    do{
        X *= 2 ;
    }while(N >= X) ;
    
    cout << X / 2 << endl ;
    
}

C++: #include<bits/stdc++.h>
using namespace std;

#define rep(i,n) for(long long i=0;i<n;i++)
#define REP(i,s,n) for(long long i=(s);i<=(n);i++)
#define repr(i,n) for(long long i=n-1;i>=0;i--)
#define REPR(i,s,n) for(long long i=(s);i>=(n);i--)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define Eunique(v) v.erase(unique(all(v)),v.end())
#define Eback(s) s.erase(s.end()-1,s.end())
#define minvec(v) *min_element(all(v))
#define maxvec(v) *max_element(all(v))
#define sumvec(v) accumulate(all(v),0LL)
#define pb push_back
#define pf push_front
#define m_p make_pair
#define DOUBLE fixed << setprecision(15)
#define OK cerr<<"OK\n"
#define OK1 cerr<<"OK1\n"
#define OK2 cerr<<"OK2\n"
#define sz(s) (long long)s.size()
#define INF ((1LL<<62)-(1LL<<31))
#define zero(x,n) setw(x) << setfill('0') << n
//#define endl '\n'

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<double> vd;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef vector<vd> vvd;
typedef vector<vc> vvc;
typedef vector<vb> vvb;
typedef pair<ll,ll> P;
typedef vector<P> vP;

template<class A, class B>
ostream& operator<<(ostream& ost, const pair<A, B>&p) {
	ost << "{" << p.first << ", " << p.second << "} ";
	return ost;
}

template<class T>
ostream& operator<<(ostream& ost, const vector<T>&v) {
	ost << "{";
	for (int i = 0; i<(int)v.size(); i++) {
		if (i)ost << " ";
		ost << v[i];
	}
	ost << "} \n";
	return ost;
}

template<class A, class B>
ostream& operator<<(ostream& ost, const map<A, B>&v) {
	ost << "{";
	for (auto p:v) {
		ost << "{" << p.first << ", " << p.second << "} ";
	}
	ost << "} ";
	return ost;
}

void out(){cout << "\n";}
template<class T,class... Args>
void out(const T &x,const Args &... args){
	cout << x << " ";
	out(args...);
}

template<typename T>
istream& operator >> (istream& is, vector<T>& vec){
	for(T& e: vec) is >> e;
	return is;
}

template<typename T>
string join(vector<T>& vec, string sep=" "){
	stringstream ss;
	for(int i=0;i<(int)vec.size();i++){
		ss << vec[i] << (i+1==(int)vec.size()?"\n":sep);
	}
	return ss.str();
}

template<class T>
inline bool chmax(T& a, T b){if(a<b){a=b;return true;} return false;}

template<class T>
inline bool chmin(T& a, T b){if(a>b){a=b;return true;} return false;}

#define INT(...) int __VA_ARGS__;IN(__VA_ARGS__)
#define LL(...) long long __VA_ARGS__;IN(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;IN(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;IN(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;IN(__VA_ARGS__)
#define LD(...) long double __VA_ARGS__;IN(__VA_ARGS__)

void scan(int& a){ cin >> a; }
void scan(long long& a){ cin >> a; }
void scan(char& a){ cin >> a; }
void scan(double& a){ cin >> a; }
void scan(string& a){ cin >> a; }
void scan(long double& a){ cin >> a; }

void IN(){}
template<class Head,class... Tail> void IN(Head& head,Tail&... tail){ scan(head); IN(tail...); }

void YES(bool b) {cout << ((b)?"YES\n":"NO\n");}
void Yes(bool b) {cout << ((b)?"Yes\n":"No\n");}
void yes(bool b) {cout << ((b)?"yes\n":"no\n");}
void Yay(bool b) {cout << ((b)?"Yay!\n":":(\n");}

const long double pi = acos(-1.0);
const ll mod=1000000007;
//const ll mod=998244353;

ll powmod(ll a,ll b){ll c=1; while(b>0){ if(b&1){ c=a*c%mod; } a=a*a%mod; b>>=1; } return c;}
ll nCrmod(ll n,ll r){ll x=1,y=1; for(ll i=0;i<r;i++) {x=x*(n-i)%mod; y=y*(i+1)%mod; } return x*powmod(y,mod-2)%mod;}
ll gcd(ll a,ll b){ while(b){ ll c=b; b=a%b; a=c; } return a; }
ll lcm(ll a,ll b){ if(!a || !b) return 0; return a*b/gcd(a,b); }
vll divisor(ll x){ vll v; for(int i=1;i*i<=x;i++)if(x%i==0){ v.pb(i);if(i*i!=x)v.pb(x/i); } sort(all(v)); return v; };
map<ll,ll> prime_factor(ll n){ map<ll,ll> m; for(ll i=2;i*i<=n;i++){ while(n%i==0){ m[i]++; n/=i; } } if(n!=1) m[n]=1; return m; }

int main()
{
    LL(n);
    ll ans = 0;
    while(pow(2, ans++) <= n);
    cout << pow(2, ans - 2) << endl;
	return 0;
}