import java.util.*;

class IPAddress

{

public static void main(String args[])

{

Scanner sc=new Scanner(System.in);

String address;

System.out.println("enter the ip adddress");

address=sc.next();

int IPVAL=0;

String classLevel="";

for(int i=0;i<3;i++)

{

int temp=address.charAt(i);

if(temp=='.')

break;

IPVAL=((IPVAL*10)+(temp-48));

}

if(IPVAL<128)

classLevel="A";

else if(IPVAL<192)

classLevel="B";

else if(IPVAL<224)

classLevel="C";

else if(IPVAL<240)

classLevel="D";

else if(IPVAL<256)

classLevel="E";

else

classLevel="invalid network ip";

System.out.print("Class:"+classLevel);

}

}