#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int n;

vector<int> divisor(int n) {
  vector<int> res;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      res.push_back(i);
      if (i * i != n) res.push_back(n / i);
    }
  }
  return res;
}
int main() {
  cin >> n;
  for (int i = n - 100; i <= i + 100; i++) {
    vector<int> res = divisor(i);
    for (int j = 0; j < res.size(); j++) {
      if (res[j] != 1 && res[j] != i) {
        cout << i << endl;
        return 0;
      }
    }
  }
  return 0;
}