#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)
#define unless(p) if(!(p))
#define until(p) while(!(p))

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    ll N;
    std::cin >> N;

    ll res = N;
    if(N % 2 == 0 && N > 4){
        res = N / 2;
    }

    for(ll i=3;i*i<=N;++i){
        if(N % i == 0){
            res = min(res, i);
        }
    }

    std::cout << res << std::endl;
}