#include <iostream>
#include <iomanip>
typedef unsigned long long ul;
typedef signed long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed << std::setprecision(2);
  ll n;
  std::cin >> n;
  for (ll i = 3; i * i <= n || i <= 9; ++i) {
    if (n%i==0) {std::cout << i << std::endl; return 0;}
  }
  std::cout << n << std::endl;
  return 0;
}