#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <string.h>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

#define FOR(i,a,b) for(ll i = (a);i<(b);i++)
#define REP(i,a) FOR(i,0,(a))
#define MP make_pair

ll getAns(ll n){
	for(ll i = 3;i * i <= n;i++){
		if(n % i == 0) return i;
	}
	if(n % 2 == 0) return n / 2;
	return n;
}

int main() {
	ll n;
	cin >> n;
	cout << getAns(n) << endl;
	return 0;
}