import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;
import java.math.BigInteger;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        C solver = new C();
        solver.solve(1, in, out);
        out.close();
    }

    static class C {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            // 入力
            int x = Integer.parseInt(in.next());
            BigInteger b = BigInteger.valueOf(x);

            // 出力
            if (isPrime(x)) {
                out.println(b.nextProbablePrime());
            } else {
                out.println(x);
            }

        }

        public static boolean isPrime(int num) {
            if (num < 2) return true;
            else if (num == 2) return false;
            else if (num % 2 == 0) return true;

            double sqrtNum = Math.sqrt(num);
            for (int i = 3; i <= sqrtNum; i += 2) {
                if (num % i == 0) {
                    return true;
                }
            }
            return false;
        }

    }
}


/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz