#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

signed main(){
  ll N; cin >> N;
  ll ans = ( ll ) 1e16;
  for( int i = 1; 1LL *  i * i <= N; ++i )
    if( N % i == 0 ){
      if( i > 2 )
        ans = min( ans, 1LL * i );
      if( N / i > 2 )
        ans = min( ans, N / i );
    }
  cout << ans << endl;
  return 0;
}