import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        sc.close();

        if (X == 2) {
            System.out.println(X);
            return;
        }
        int ans = X;
        for (int x = X; x < X * 2; x++) {
            if (x % 2 == 0) continue;
            int sqrt = (int) Math.sqrt(x);
            boolean s = false;
            for (int j = 3; !s && j <= sqrt; j += 2) {
                if (x % j == 0) s = true;
            }
            if (!s) {
                ans = x;
                break;
            }
        }

        System.out.println(ans);
    }
}
/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