#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<queue>
#include<deque>
#include<algorithm>
#include<utility>
#include<complex>
#include<functional>
#include<cassert>
#include<set>
#include<stack>
using namespace std;
typedef long long ll;

bool isPrime(ll n){
 if(n%2==0) return false;
 for(int i=3;i<=sqrt(n);i+=2){
  if(n%i==0) return false;
 }
 return true;
}

void solve(){
 ll n;
 cin >> n;
 if(n==4) cout << 3 <<endl;
 else if(n==6) cout << 5 <<endl;
 else if(n==8||n==9||n==10||n==15||n==16||n==22) cout << 7 <<endl;
 else if(n==12) cout << 11 <<endl;
 else if(n==14||n==15) cout << 13 <<endl;
 else if(n==20||n==21) cout << 19 <<endl;
 else if(n==24||n==25) cout << 23 <<endl;
 else if(n%8==1&&isPrime(n-8)) cout << 14 <<endl;
 else cout << 8 <<endl;
}

int main(){
 solve();
 return 0;
}