#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(v) v.begin(),v.end()
typedef long long ll;

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

ll n;
ll powpow(ll x,ll m){
  ll y=x;
  ll ans=1;
  while(m){
    if(m&1){
      if(log10(ans)+log10(x)>18) return -1;
      ans=ans*x;
    }
    m/=2;
    if(m!=0 && x>1e9) return -1;
    x=x*x;
  }
  return ans;
}

int main(){
  cin>>n;
  if(n==1){
    cout<<2<<endl;
    return 0;
  }
  if(n==2){
    cout<<3<<endl;
    return 0;
  }
  
  for(ll p=2;p<=1000010;p++){
    for(ll k=2;k<41;k++){
      ll tmp=powpow(p,k);
      if(tmp==-1) break;
      ll t=(tmp-1)/(p-1);
      if(t>n) break;
      if(n%t!=0) continue;
      if(n/t<p){
        cout<<p<<endl;
        return 0;
      }
    }
  }
  cout<<n-1<<endl;

  return 0;
}