/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
for(int i=1,s;i++<999;)l:{for(s=2;s<i;)if(i%s++<1)break l;System.out.print(i<997?i+":":i);}
	}
}