import java.io.*;

class lucky

{

public static int counter = 2;

static boolean isLucky(int n)

{

int next_position = n;

if(counter > n)

return true;

if(n%counter == 0)

return false;

next_position -= next_position/counter;

counter++;

return isLucky(next_position);

}

public static void main (String[] args)

{

int x = 5;

if( isLucky(x) )

System.out.println(x+" is a lucky no.");

else

System.out.println(x+" is not a lucky no.");

}

}