#include <bits/stdc++.h>

const long mod = 1000000007;

int main() {

  long N;
  std::cin >> N;

  for(long m = 3; m < sqrt(N) + 100; ++m) {
    if( N % m == 0 ) {
      std::cout << m << std::endl;
      return 0;
    }
  }

  std::cout << N << std::endl;
  
  return 0;
}