#include <bits/stdc++.h>

using namespace std;

struct Initializer {
  Initializer() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(15);
  }
} initializer;

template<typename T> inline istream& operator>>(istream &s, vector<T> &v) {
  for (T &t : v) s >> t;
  return s;
}

template<typename T> inline ostream& operator<<(ostream &s, const vector<T> &v) {
  for (const T &t : v) s << t << endl;
  return s;
}

template<typename T> inline T min(vector<T>& v) {return *min_element(v.begin(), v.end());}

template<typename T> inline T max(vector<T>& v) {return *max_element(v.begin(), v.end());}

template<typename T> inline int min_element(vector<T>& v) {return min_element(v.begin(), v.end()) - v.begin();}

template<typename T> inline int max_element(vector<T>& v) {return max_element(v.begin(), v.end()) - v.begin();}

template<typename T> inline void sort(vector<T>& v) {sort(v.begin(), v.end());}

template<typename T, typename Function> inline void sort(vector<T>& v, Function func) {sort(v.begin(), v.end(), func);}

template<typename T> inline void rsort(vector<T>& v) {sort(v.rbegin(), v.rend());}

template<typename T> inline void reverse(vector<T>& v) {reverse(v.begin(), v.end());}

template<typename T> inline void unique(vector<T>& v) {v.erase(unique(v.begin(), v.end()), v.end());}

template<typename T> inline void nth_element(vector<T>& v, int n) {nth_element(v.begin(), v.begin() + n, v.end());}

template<typename T> inline bool next_permutation(vector<T>& v) {return next_permutation(v.begin(), v.end());}

template<typename T> inline int find(vector<T>& v, T t) {return find(v.begin(), v.end(), t) - v.begin();}

template<typename T> inline int in(vector<T> v, T t) {return find(v, t) != (int)v.size();}

template<typename T> inline int lower_bound(vector<T>& v, T t) {return lower_bound(v.begin(), v.end(), t) - v.begin();}

template<typename T> inline int upper_bound(vector<T>& v, T t) {return upper_bound(v.begin(), v.end(), t) - v.begin();}

template<typename T> inline T accumulate(const vector<T>& v, function<T(T, T)> func = plus<T>()) {return accumulate(v.begin(), v.end(), T(), func);}

template<typename T> inline void adjacent_difference(vector<T>& v) {adjacent_difference(v.begin(), v.end(), v.begin());}

template<typename T> inline void adjacent_difference(vector<T>& v, vector<T>& u) {adjacent_difference(v.begin(), v.end(), u.begin());}

template<typename T> inline void partial_sum(vector<T>& v, vector<T>& u) {partial_sum(v.begin(), v.end(), u.begin());}

template<typename T> inline T inner_product(vector<T>& v, vector<T>& u) {return inner_product(v.begin(), v.end(), u.begin(), T(0));}

template<typename T> inline int count(const vector<T>& v, T t) {return count(v.begin(), v.end(), t);}

template<typename T, typename Function> inline int count_if(const vector<T>& v, Function func) {return count_if(v.begin(), v.end(), func);}

template<typename T, typename Function> inline void remove_if(vector<T>& v, Function func) {v.erase(remove_if(v.begin(), v.end(), func), v.end());}

template<typename T, typename Function> inline bool any_of(vector<T> v, Function func) {return any_of(v.begin(), v.end(), func);}

template<typename T> inline vector<T> subvector(vector<T>& v, int a, int b) {return vector<T>(v.begin() + a, v.begin() + b);}

template<typename T> inline int kinds(const vector<T>& v) {return set<T>(v.begin(), v.end()).size();}

class Prime {
private:
  vector<long long> div;
  
public:
  Prime(long long n = 0) {
    for (long long i = 0; i <= n; ++i) div.emplace_back(i);
    for (long long i = 2; i <= n / i; ++i) if (div[i] == i) {
      for (long long j = i * i; j <= n; j += i) div[j] = i;
    }
  }
  
  bool isPrime(long long n) const {
    if (n <= 1) return false;
    if (n < (long long)div.size()) return div[n] == n;
    for (long long i = 2; i <= n / i; ++i) if (n % i == 0) return false;
    return true;
  }
  
  vector<long long> factor(long long n) const {
    vector<long long> res;
    for (long long i = 2; i <= n / i && n >= (long long)div.size(); ++i) {
      while (n % i == 0) {
        res.emplace_back(i);
        n /= i;
      }
    }
    if (n >= max((long long)div.size(), 2ll)) {
      res.emplace_back(n);
    } else {
      while (n > 1) {
        res.emplace_back(div[n]);
        n /= div[n];
      }
    }
    sort(res.begin(), res.end());
    return res;
  }
  
  vector<long long> primeFactor(long long n) const {
    vector<long long> res;
    for (long long i = 2; i <= n / i && n >= (long long)div.size(); ++i) {
      if (n % i) continue;
      res.emplace_back(i);
      while (n % i == 0) n /= i;
    }
    if (n >= max((long long)div.size(), 2ll)) {
      res.emplace_back(n);
    } else {
      while (n > 1) {
        long long d = div[n];
        res.emplace_back(d);
        while (n % d == 0) n /= d;
      }
    }
    sort(res.begin(), res.end());
    return res;
  }

  vector<long long> divisor(long long n) const {
    vector<long long> res;
    for (long long i = 1; i <= n / i; ++i) {
      if (n % i == 0) {
        res.emplace_back(i);
        if (i != n / i) res.emplace_back(n / i);
      }
    }
    sort(res.begin(), res.end());
    return res;
  }
};

int main() {
  int64_t n;
  cin >> n;
  Prime prime;
  auto d = prime.divisor(n);
  cout << d[lower_bound(d, 3ll)] << endl;
}