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

#define ll         long long
#define PI         acos(-1.0)
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)

int main(){
    ll int n;
    cin >> n;
    ll int i;
    for(i=3; (i*i)<n; ++i){
        if(n%i==0){
            cout << i << endl;
            return 0;
        }
    }
    if(i*i==n){
        cout << i << endl;
        return 0;
    }
    if(n%2==0 && n!=4){
        cout << n/2 << endl;
          return 0;
    }
    cout << n << endl;
}