#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cmath>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <functional>
#include <set>
#include <numeric>
#include <stack>
#include <utility>
//#include "util.h"

using namespace std;
typedef long long lint;
typedef pair<lint, lint> Pii;

#define PI 3.14159265358979323846
#define EPS 1e-6
#define MOD ((lint)1000000007)
#define MIN(a,b) ((a)<(b)?(a):(b))
#define MAX(a,b) ((a)>(b)?(a):(b))

int main()
{
	vector<bool> c(2048, false);
	for (int i = 2; i * i <= 1100; i++)
		if (!c[i])
			for (int j = i * i; j <= 1100; j += i)
				c[j] = true;

	int N;
	cin >> N;
	for (int i = N - 100; i <= N + 100; i++) {
		if (c[i]) {
			cout << i << endl;
			return 0;
		}
	}
	
	return 0;
}