//No.192 合成数

import java.util.*;
import java.io.*;
import static java.util.Arrays.*;
import static java.lang.Math.*;

public class No0192 {
    
    static final Scanner in = new Scanner(System.in);
    static final PrintWriter out = new PrintWriter(System.out,false);

    static void solve() {
        boolean[] isPrime = sieveOfEratosthenes(2000);
        int n = in.nextInt();
        for (int i=n-100; i<=n+100; i++) {
            if (!isPrime[i] && i != 1) {
                out.println(i);
                return;
            }
        }
    }

    static boolean[] sieveOfEratosthenes(int n) {
        boolean[] isPrime = new boolean[n];
        Arrays.fill(isPrime,true);
        isPrime[0] = isPrime[1] = false;
        for (int i=2; i<n; i++) {
            if (isPrime[i]) {
                for (int j=i+i; j<n; j+=i) isPrime[j] = false;
            }
        }
        return isPrime;
    }

    public static void main(String[] args) {
        long start = System.currentTimeMillis();

        solve();
        out.flush();

        long end = System.currentTimeMillis();
        //trace(end-start + "ms");
        in.close();
        out.close();
    }

    static void trace(Object... o) { System.out.println(deepToString(o));}
}