#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  ll n;
  cin >> n;
  for (ll x = 3; x <= n; ++x) {
    if (n % x == 0) {
      cout << x << '\n';
      return 0;
    }
    if (x > 2'000'000) break;
  }
  cout << n << '\n';
  return 0;
}