#include <bits/stdc++.h>
using namespace std;
#define Rep(i,n) for(int i=0;i<(int)(n);i++)
#define For(i,n1,n2) for(int i=(int)(n1);i<(int)(n2);i++)
#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define RREP(i,n) for(ll i=((ll)(n)-1);i>=0;i--)
#define FOR(i,n1,n2) for(ll i=(ll)(n1);i<(ll)(n2);i++)
#define RFOR(i,n1,n2) for(ll i=((ll)(n1)-1);i>=(ll)(n2);i--)
#define all(a)  (a).begin(),(a).end()
#define SORT(a) sort((a).begin(),(a).end())
#define oorret 0
#define oor(x) [&](){try{x;} catch(const out_of_range& oor){return oorret;} return x;}()
#define IOS cin.tie(0),ios::sync_with_stdio(false)
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
template<typename T1, typename T2> inline bool chmin(T1& a, T2 b) { if (a > b) { a = b; return 1; }return 0; }
template<typename T1, typename T2> inline bool chmax(T1& a, T2 b) { if (a < b) { a = b; return 1; }return 0; }
template<class Type>struct is_vector : std::false_type {};
template<class ValueType, class Alloc>struct is_vector<std::vector<ValueType, Alloc>> : std::true_type {};
template <typename T> inline ostream& operator << (ostream& out, const vector<T>& v) {
	if (v.empty())return out;
	constexpr bool is_vector_v = is_vector<T>::value;
	if (is_vector_v)for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? "\n" : "");
	else for (auto itr = v.begin(); itr != v.end();)out << (*itr), out << ((++itr != v.end()) ? " " : "");
	return out;
}
inline void put() {}
template<class T> inline void put(const T& first) { std::cout << first << "\n"; }
template<class T, class... N> inline void put(const T& first, const N& ... rest) { std::cout << first << " "; put(rest...); }
inline void putn() {}
template<class T, class... N> inline void putn(const T& first, const N& ... rest) { std::cout << first << "\n"; putn(rest...); }

using u32 = unsigned int;
using u64 = unsigned long long;
using u128 = __uint128_t;

template <class Uint, class BinOp>
bool is_prime_impl(const Uint& n, const Uint* witness, BinOp modmul) {
	if (n == 2) return true;
	if (n < 2 || n % 2 == 0) return false;
	const Uint m = n - 1, d = m / (m & -m);
	auto modpow = [&](Uint a, Uint b) {
		Uint res = 1;
		for (; b; b /= 2) {
			if (b & 1) res = modmul(res, a);
			a = modmul(a, a);
		}
		return res;
	};
	auto suspect = [&](Uint a, Uint t) {
		a = modpow(a, t);
		while (t != n - 1 && a != 1 && a != n - 1) {
			a = modmul(a, a);
			t = modmul(t, 2);
		}
		return a == n - 1 || t % 2 == 1;
	};
	for (const Uint* w = witness; *w; w++) {
		if (*w % n != 0 && !suspect(*w, d)) return false;
	}
	return true;
}

bool is_prime(const u128& n) {
	//assert(n < 1ULL << 63);
	if (n < 1ULL << 32) {
		// n < 2^32
		constexpr u64 witness[] = { 2, 7, 61, 0 };
		auto modmul = [&](u64 a, u64 b) { return a * b % n; };
		return is_prime_impl<u64>(n, witness, modmul);
	} else {
		// n < 2^63
		constexpr u128 witness[] = { 2, 325, 9375, 28178, 450775, 9780504, 1795265022, 0 };
		auto modmul = [&](u128 a, u128 b) { return a * b % n; };
		return is_prime_impl<u128>(n, witness, modmul);
	}
}


int main() {
	IOS;
	int x;
	cin >> x;
	int res = x;
	while (!is_prime(res)) {
		res++;
	}
	put(res);
	return 0;
}

Measured memory_bytes: 384