#include <iostream>
#include <vector>
using namespace std;
typedef long long ll;

ll solve(ll N){
  vector<ll> divisors;
  for(ll d=1;d*d<=N;d++){
    if(N % d == 0){
      divisors.push_back(d);
      if(N / d != d){
        divisors.push_back(N / d);
      }
    }
  }
  ll res = N;
  for(ll d : divisors){
    if(d > 2){
      res = min(res, d);
    }
  }
  return res;
}

int main(){
  ll N;
  cin >> N;
  cout << solve(N) << endl;
  return 0;
}