#include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(),(c).end()
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i,n) REP(i,0,n)
#define iter(c) __typeof((c).begin())
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
#define pb(a) push_back(a)
#define pr(a) cout<<(a)<<endl
#define PR(a,b) cout<<(a)<<" "<<(b)<<endl
#define R cin>>
#define F first
#define S second
#define ll long long
bool check(int n,int m,int x,int y){return x>=0&&x<n&&y>=0&&y<m;}
const ll MAX=1000000007,MAXL=1LL<<60,dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
typedef pair<int,int> P;

vector<int> sieve(int n) {
  vector<int> p(n);
  for(int i=1; i<n; i++) p[i]=i;
  for(int i=2; i*i<n; i++) {
    if(p[i]) {
      for(int j=i*i; j<n; j+=i) p[j]=0;
    }
  }
  return p;
}

int main() {
  int n;
  cin >> n;
  vector<int> p=sieve(100000);
  int ans=0;
  REP(i,n-100,n+101) {
    if(!p[i]) ans=i;
  }
  cout << ans << endl;
  return 0;
}