import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import static java.lang.System.in;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        int N = Integer.parseInt(reader.readLine());
        int compositeNumber = 0;
        for (int i = N - 100; i <= N + 100; i++) {
            for (int j = 2; j * j <= i; j++) {
                if (i % j == 0) {
                    compositeNumber = i;
                }
            }
        }
        System.out.println(compositeNumber);
    }
}