#include <bits/stdc++.h>
typedef  long long ll;
#define INF 1000000000
using namespace std;
#define N 1000000
#define MOD 1000000007
int main(void){
    ll n;
    cin>>n; 
    vector<ll> ret;
	for(ll i=3 ; i<=sqrt(n) ; i++)
	{
        if(n%i==0){
            cout<<i<<endl;
            return 0;
        }
	}
    if(n%2==0&&n/2!=2){
        cout<<n/2<<endl;
    }else{
        cout<<n<<endl;
    }
}