// Original C++ solution (slower):
#pragma region header

#include <bits/stdc++.h>

#define int long long

#define all(a) begin(a), end(a)

#define rall(a) rbegin(a), rend(a)

#define mp make_pair

#define rep1(i, n) for (decltype(+n) i = 0; i < (n); i++)

#define rrep1(i, n) for (auto i = n - 1; i > static_cast<decltype(i)>(-1); i--)

#define rep2(i, a, b) for (auto i = (a); i < (b); i++)

#define rrep2(i, a, b) for (auto i = b - 1; i >= a; i--)

#define GET_MACRO(_1, _2, _3, NAME, ...) NAME

#define rep(...) GET_MACRO(__VA_ARGS__, rep2, rep1) (__VA_ARGS__)

#define rrep(...) GET_MACRO(__VA_ARGS__, rrep2, rrep1) (__VA_ARGS__)

#define each(i, a) for (auto &&i : (a))

using namespace std;



using ld = long double;

using vi = vector<int>;

using vvi = vector<vi>;

using vs = vector<string>;

using vvs = vector<vs>;

using vd = vector<ld>;

using vvd = vector<vd>;

using vb = vector<bool>;

using vvb = vector<vb>;

using pii = pair<int, int>;

using vp = vector<pii>;

using vvp = vector<vp>;

using mii = map<int, int>;

using vm = vector<mii>;

using vvm = vector<vm>;

template <class T, class U>

using umap = unordered_map<T, U>;

using umii = umap<int, int>;

using seti = set<int>;

template <class T>

using uset = unordered_set<T>;

using useti = uset<int>;

template <class T>

using less_queue = priority_queue<T>;

template <class T>

using greater_queue = priority_queue<T, vector<T>, greater<T>>;

using int128 = __int128_t;



ostream &operator<<(ostream &dest, int128 value) {

  ostream::sentry s(dest);

  if (s) {

    int128 tmp = value < 0 ? -value : value;

    char buffer[128];

    char *d = end(buffer);

    do {

      --d;

      *d = "0123456789"[tmp % 10];

      tmp /= 10;

    } while (tmp != 0);

    if (value < 0) {

      --d;

      *d = '-';

    }

    int len = end(buffer) - d;

    if (dest.rdbuf()->sputn(d, len) != len) {

      dest.setstate(ios_base::badbit);

    }

  }

  return dest;

}



const int INF = 1e18;

const ld EPS = 1e-10;



template <class T>

void SORT(T &a) { stable_sort(all(a)); }

template <class T>

void RSORT(T &a) { stable_sort(rall(a)); }

template <class T>

void rev(T &a) { reverse(all(a)); }

template <class T>

void uniq(T &a) { a.erase(unique(all(a)), end(a)); }

template <class T>

auto min_of(const T &a) { return *min_element(all(a)); }

template <class T>

auto max_of(const T &a) { return *max_element(all(a)); }

template <class T>

T sum_of(const vector<T> &a) { return accumulate(all(a), (T)0); }

template <class T, class U>

int count_of(const T &a, const U &i) { return count(all(a), i); }

template <class T>

bool has(const vector<T> &a, const T &i) { return find(all(a), i) != a.end(); }

bool has(const string &a, const char &i) { return find(all(a), i) != a.end(); }

template <class T>

bool has(const set<T> &a, const T &i) { return a.find(i) != a.end(); }

template <class T, class U>

bool has(const map<T, U> &a, const T &i) { return a.find(i) != a.end(); }

template <class T, class U>

bool has(const umap<T, U> &a, const T &i) { return a.find(i) != a.end(); }

template <class T>

int sz(const T &a) { return a.size(); };



template <class T>

void COUT(const T &x) { cout << x << endl; }

template <class T, class U>

void COUT(const T &x, const U &y) { cout << x << ' ' << y << endl; }

template <class T, class U, class V>

void COUT(const T &x, const U &y, const V &z) { cout << x << ' ' << y << ' ' << z << endl; }

template <class T>

void CSP(const T &x) { cout << x << ' '; }

template <class T>

void CVEC(const T &v) {

  int c = v.size() - 1;

  for (int i = 0; i < c; i++) cout << v[i] << ' ';

  if (c > -1) cout << v[c];

  cout << endl;

}



template <class T>

bool amin(T &a, const T &b) {

  if (a > b) {

    a = b;

    return true;

  }

  return false;

}

template <class T>

bool amax(T &a, const T &b) {

  if (a < b) {

    a = b;

    return true;

  }

  return false;

}



constexpr int lshift(const int &x) noexcept { return 1ll << x; }

constexpr int popcount(const unsigned int &x) noexcept { return __builtin_popcountll(x); }

constexpr int least1(const unsigned int &x) noexcept { return __builtin_ffsll(x); }

constexpr int ceil_div(const int &x, const int &y) noexcept { return (x + y - 1) / y; }



#pragma endregion header



// vb prime_table(int n) {

//   vb prime(n + 1, true);

//   if (n >= 0) prime[0] = false;

//   if (n >= 1) prime[1] = false;

//   for (int i = 2; i * i <= n; i++)

//     if (prime[i]) for (int j = i + i; j <= n; j += i) prime[j] = false;

//   return prime;

// }



template<int N>

struct prime_table {

  bool prime[N + 1];

  constexpr prime_table() noexcept : prime() {

    memset(prime, true, sizeof(prime));

    if (N >= 0) prime[0] = false;

    if (N >= 1) prime[1] = false;

    for (int i = 2; i * i <= N; i++)

      if (prime[i]) for (int j = i + i; j <= N; j += i) prime[j] = false;

  }

  constexpr bool operator()(const int& i) const noexcept { return prime[i]; }

};

const prime_table<100003> pt;



void solve(int X) {

  rep(i, X, INF) if(pt(i)) {

    COUT(i);

    return;

  }

}





#pragma region main

signed main() {

  ios_base::sync_with_stdio(0);

  cin.tie(0);

  cout.tie(0);

  cout << fixed << setprecision(15);



  int X;

  cin >> X;

  solve(X);

}

#pragma endregion main


// Optimized solution to the same problem (faster):
#pragma region header

#include <bits/stdc++.h>

#define int long long

#define all(a) begin(a), end(a)

#define rall(a) rbegin(a), rend(a)

#define mp make_pair

#define rep1(i, n) for (decltype(+n) i = 0; i < (n); i++)

#define rrep1(i, n) for (auto i = n - 1; i > static_cast<decltype(i)>(-1); i--)

#define rep2(i, a, b) for (auto i = (a); i < (b); i++)

#define rrep2(i, a, b) for (auto i = b - 1; i >= a; i--)

#define GET_MACRO(_1, _2, _3, NAME, ...) NAME

#define rep(...) GET_MACRO(__VA_ARGS__, rep2, rep1) (__VA_ARGS__)

#define rrep(...) GET_MACRO(__VA_ARGS__, rrep2, rrep1) (__VA_ARGS__)

#define each(i, a) for (auto &&i : (a))

using namespace std;



using ld = long double;

using vi = vector<int>;

using vvi = vector<vi>;

using vs = vector<string>;

using vvs = vector<vs>;

using vd = vector<ld>;

using vvd = vector<vd>;

using vb = vector<bool>;

using vvb = vector<vb>;

using pii = pair<int, int>;

using vp = vector<pii>;

using vvp = vector<vp>;

using mii = map<int, int>;

using vm = vector<mii>;

using vvm = vector<vm>;

template <class T, class U>

using umap = unordered_map<T, U>;

using umii = umap<int, int>;

using seti = set<int>;

template <class T>

using uset = unordered_set<T>;

using useti = uset<int>;

template <class T>

using less_queue = priority_queue<T>;

template <class T>

using greater_queue = priority_queue<T, vector<T>, greater<T>>;

using int128 = __int128_t;



ostream &operator<<(ostream &dest, int128 value) {

  ostream::sentry s(dest);

  if (s) {

    int128 tmp = value < 0 ? -value : value;

    char buffer[128];

    char *d = end(buffer);

    do {

      --d;

      *d = "0123456789"[tmp % 10];

      tmp /= 10;

    } while (tmp != 0);

    if (value < 0) {

      --d;

      *d = '-';

    }

    int len = end(buffer) - d;

    if (dest.rdbuf()->sputn(d, len) != len) {

      dest.setstate(ios_base::badbit);

    }

  }

  return dest;

}



const int INF = 1e18;

const ld EPS = 1e-10;



template <class T>

void SORT(T &a) { stable_sort(all(a)); }

template <class T>

void RSORT(T &a) { stable_sort(rall(a)); }

template <class T>

void rev(T &a) { reverse(all(a)); }

template <class T>

void uniq(T &a) { a.erase(unique(all(a)), end(a)); }

template <class T>

auto min_of(const T &a) { return *min_element(all(a)); }

template <class T>

auto max_of(const T &a) { return *max_element(all(a)); }

template <class T>

T sum_of(const vector<T> &a) { return accumulate(all(a), (T)0); }

template <class T, class U>

int count_of(const T &a, const U &i) { return count(all(a), i); }

template <class T>

bool has(const vector<T> &a, const T &i) { return find(all(a), i) != a.end(); }

bool has(const string &a, const char &i) { return find(all(a), i) != a.end(); }

template <class T>

bool has(const set<T> &a, const T &i) { return a.find(i) != a.end(); }

template <class T, class U>

bool has(const map<T, U> &a, const T &i) { return a.find(i) != a.end(); }

template <class T, class U>

bool has(const umap<T, U> &a, const T &i) { return a.find(i) != a.end(); }

template <class T>

int sz(const T &a) { return a.size(); };



template <class T>

void COUT(const T &x) { cout << x << endl; }

template <class T, class U>

void COUT(const T &x, const U &y) { cout << x << ' ' << y << endl; }

template <class T, class U, class V>

void COUT(const T &x, const U &y, const V &z) { cout << x << ' ' << y << ' ' << z << endl; }

template <class T>

void CSP(const T &x) { cout << x << ' '; }

template <class T>

void CVEC(const T &v) {

  int c = v.size() - 1;

  for (int i = 0; i < c; i++) cout << v[i] << ' ';

  if (c > -1) cout << v[c];

  cout << endl;

}



template <class T>

bool amin(T &a, const T &b) {

  if (a > b) {

    a = b;

    return true;

  }

  return false;

}

template <class T>

bool amax(T &a, const T &b) {

  if (a < b) {

    a = b;

    return true;

  }

  return false;

}



constexpr int lshift(const int &x) noexcept { return 1ll << x; }

constexpr int popcount(const unsigned int &x) noexcept { return __builtin_popcountll(x); }

constexpr int least1(const unsigned int &x) noexcept { return __builtin_ffsll(x); }

constexpr int ceil_div(const int &x, const int &y) noexcept { return (x + y - 1) / y; }



#pragma endregion header



vb prime_table(int n) {

  vb prime(n + 1, true);

  if (n >= 0) prime[0] = false;

  if (n >= 1) prime[1] = false;

  for (int i = 2; i * i <= n; i++)

    if (prime[i]) for (int j = i + i; j <= n; j += i) prime[j] = false;

  return prime;

}



void solve(int X) {

  vb pt = prime_table(100003);

  rep(i, X, INF) if(pt[i]) {

    COUT(i);

    return;

  }

}





#pragma region main

signed main() {

  ios_base::sync_with_stdio(0);

  cin.tie(0);

  cout.tie(0);

  cout << fixed << setprecision(15);



  int X;

  cin >> X;

  solve(X);

}

#pragma endregion main


// Fastest known solution for this problem: