#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;

vector<int> divisor(int n){
  vector<int> ret;
  for(int i=1; i*i<=n; i++){
    if(n%i==0){
      ret.push_back(i);
      if(i!=n/i) ret.push_back(n/i);
    }
  }
  return ret;
}

int main(){
  int N;
  cin >> N;
  for(int i=N-100; i<=N+100; i++){
    vector<int> res = divisor(i);
    if(res.size() > 2){
      cout << i << endl;
      break;
    }
  }
  return 0;
}