893B - Beautiful Divisors - CodeForces Solution

#include <iostream>
#include <algorithm>
#include <iomanip>
#include <string>
#include <cmath>
#include <vector>
#include<stdio.h>
#include<string.h>
#include<bitset>
#include <map>
#include <unordered_map>
#include <stack>
#include <set>


using namespace std;

#define _CRT_SECURE_NO_WARNINGS
#define sobhi ios_base::sync_with_stdio(false);cout.tie(NULL);cin.tie(NULL);
#define mod	1000000007
#define PI 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679
//*************************************************************************************//
#define ll long long
#define fixed(n) cout << fixed << setprecision(n);
#define test() ll t;cin>>t;while(t--)
#define v vector
#define so(vec) sort(vec.begin(), vec.end());
#define all(vec) vec.begin(), vec.end()
#define rall(x) (x).rbegin(), (x).rend()
#define sor(arr,n) sort(arr, arr+n);
#define for0(i,n)             for (ll i=0;i<n;i++)
#define for1(i,n)             for(ll i=1;i<=n;i++)
#define i(l,n,s) for (ll i = l; i < n; i+=s)
#define j(l,n,s) for (ll j = l; j < n; j+=s)
#define ri(l,n,s) for (ll i = n; i >=l; i-=s)
#define rj(l,n,s) for (ll j = n; j >=l; j-=s)
const ll MAX = 1e5 + 7;

template <typename T> istream& operator>>(istream& in, vector <T>& a) { for (auto& i : a) in >> i; return in; }
template <typename T> ostream& operator<<(ostream& out, vector <T>& a) { for (auto& i : a) out << i << " "; return out; }

string abc = "abcdefghijklmnopqrstuvwxyz";
string ABC = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
string number = "0123456789";

v<ll>a[MAX];
bool vis[MAX];
ll c, d;
//void dfs(int node)
//{
//	vis[node] = 1;
//	i(0, adj[node].size(), 1)
//	{
//		int n = adj[node][i];
//		if (!vis[n])dfs(n);
//	}
//}
void dfs(int u)
{
	vis[u] = 1;
	for0(i, a[u].size())
	{
		ll x = a[u][i];
		if (vis[x])
		{
			d = 1;
			break;
		}
		else
		{
			c++;
			dfs(x);
		}
	}
}

ll fact(ll n) {
	if (n == 0 || n == 1)return n;
	return n * fact(n - 1);
}

ll gcd(ll a, ll b) {
	return ((b == 0) ? a : gcd(b, a % b));
}
int com(pair<int, int>& a, pair<int, int>& b) {
	return a.second > b.second;
}
int main()
{
	//freopen("flips.in", "r", stdin);
	//freopen("output.txt", "w", stdout);
	sobhi
		ll n; cin >> n;
	ll k = 1,tmp=1,ans=1;
	while (n >= tmp)
	{
		if (n % tmp == 0) 
			ans = tmp;
		k++;
		tmp = (pow(2, k) - 1) * (pow(2, k - 1));
	}
	cout << ans;
	return 0;
}