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

public class Main {
	public static void main(String args[]) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String line = br.readLine();
		int n = Integer.parseInt(line);
		int min = n - 100;
		if (min < 3) {
			min = 3;
		}
		
		int max = n + 100;
		
		if (n % 2 == 0) {
			System.out.println(n);
			return;
		}
		
		for (int i = min; i < max; i ++) {
			for (int j = 2; j < i; j+=2) {
				if (i % j == 0) {
					System.out.println(i);
					return;
				}
			}
		}
	}
}