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

bool f(ll n, ll p){
  bool flag = true;
  int a = n%p;
  ll pow = p;
  while(n/pow>0){
    int b = (n/pow)%p;
    if(b!=a){
      flag = false;
      break;
    }
    pow *= p;
  }
  return flag;
}

int main(){
  ll n; cin >> n;
  ll ans = 0;
  for(int i = 2; i*i <= n; i++){
    if(f(n, i)){
      ans = i;
      break;
    }
  }
  if(ans==0) ans = n-1;
  cout << ans << endl;
  return 0;
}