#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

int main(){
  int N; cin >> N;
  vector<int> X(1601, 1);
  X[0] = 0;
  for(int i = 2; i <= (int)sqrt(N); i++){
    for(int j = i; j <= 1600; j += i){
      X[j]++;
    }
  }
  for(int i = N-100; i <= N+100; i++){
    if(X[i] > 2){
      cout << i << endl;
      return 0;
    }
  }
}