#include <iostream>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <algorithm>
const int mod=1e9+7;
using LL=long long;
using std::cout;using std::endl;using std::cin;
using std::vector;using std::string;using std::set;using std::multiset;
using std::pair;using std::map;
using std::min;using std::max;
using std::make_pair;using std::swap;
std::ostream& operator<<(std::ostream& os,std::map<int,int>& obj){for(std::map<int,int>::iterator itr=obj.begin();itr!=obj.end();itr++){os<<itr->first<<"^"<<itr->second<<" ";}return os;}
std::ostream& operator<<(std::ostream& os,std::vector<std::map<int,int>>& obj){for(auto itr=obj.begin();itr!=obj.end();itr++){os<<*itr<<std::endl;}return os;}
std::ostream& operator<<(std::ostream& os,std::vector<int>& obj){for(auto itr=obj.begin();itr!=obj.end();itr++){os<<*itr<<" ";}return os;}
std::ostream& operator<<(std::ostream& os,std::vector<std::vector<int>>& obj){for(auto itr=obj.begin();itr!=obj.end();itr++){os<<*itr<<std::endl;}return os;}

namespace ndifix{
template<class T> void sort(T &v){std::sort(v.begin(),v.end());}
template<class T> void rsort(T &v){std::sort(v.rbegin(),v.rend());}

}


int main(){
  int n;cin>>n;
  vector<int> prime;
  prime.push_back(3);
  for(int i=5;i<1200;i+=2){
    bool flag=1;
    for(int j=0;j<prime.size();j++){
      if(i%prime[j]==0){flag=0;break;}
    }
    if(flag)prime.push_back(i);
  }
  prime.push_back(2);
  prime.push_back(1);
  ndifix::sort(prime);
  for(int i=n-100;i<n+101;i++){
    if(i==prime[0])prime.erase(prime.begin());
    else if(i>prime[0])prime.erase(prime.begin());
    else {cout<<i<<endl;return 0;}
  }
  return 0;
}