#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;
#define len(n) (int)n.length()
#define pb push_back
#define ll long long
#define make_pair mkp
#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define ALL(v) (v).begin(), (v).end()
#ifdef DBGPRT
#define dbg(n) cerr << "//" << #n << ":" << n <<endl
#else
#define dbg(n) ;
#endif
typedef pair<ll, ll> LLARR;
#define INF 999999999
const double PI = 3.1415926535897932384626433832795;

int main()
{
	ios::sync_with_stdio(false);

	ll n;
	cin >> n;
	ll max = sqrt(n);
	ll ans = -1;
	for(ll i = 3; i <= max; i++)
	{
		if (n % i == 0)
		{
			ans = i;
			break;
		}
	}
	if (ans == -1)
	{
		if (n % 2 == 0)
			cout << n / 2 << endl;
		else
			cout << n << endl;
	}
	else
	{
		cout << ans << endl;
	}
	
	return 0;
}