#include<bits/stdc++.h>
using namespace std;

#define int long long

typedef pair<int,int>pint;
typedef vector<int>vint;
#define pb push_back
#define mp make_pair
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
template<class T,class U>void chmin(T &t,U f){if(t>f)t=f;}
template<class T,class U>void chmax(T &t,U f){if(t<f)t=f;}

signed main(){
    int N;cin>>N;
    for(int i=3;i*i<=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;
    return 0;
}