import java.util.*;
public class Main {
	public static void main(String[] args){
	   Scanner sc = new Scanner(System.in);
	   String str = sc.next();
      
      if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	}
        
      }
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
	   Scanner sc = new Scanner(System.in);
	   String str = sc.next();
      
      if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	}
        
      }
} Main public static void main(String[] args){
	   Scanner sc = new Scanner(System.in);
	   String str = sc.next();
      
      if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	}
        
      } main {
	   Scanner sc = new Scanner(System.in);
	   String str = sc.next();
      
      if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	}
        
      } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String str = sc.next(); str sc.next() sc.next sc if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	} str.length()==1 && !str.equals("@") str.length()==1 str.length() str.length str 1 !str.equals("@") str.equals("@") str.equals str "@" {
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	} if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      } Character.isUpperCase(str.charAt(0)) Character.isUpperCase Character str.charAt(0) str.charAt str 0 {
      	str = "A";
      } str = "A" str "A" {
        str = "a";
      } str = "a" str "a" System.out.println(str) System.out.println System.out System System.out str String[] args args public class Main {
	public static void main(String[] args){
	   Scanner sc = new Scanner(System.in);
	   String str = sc.next();
      
      if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	}
        
      }
} public class Main {
	public static void main(String[] args){
	   Scanner sc = new Scanner(System.in);
	   String str = sc.next();
      
      if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	}
        
      }
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
	   Scanner sc = new Scanner(System.in);
	   String str = sc.next();
      
      if(str.length()==1 && !str.equals("@")){
 
      if(Character.isUpperCase(str.charAt(0))){
      	str = "A";
      }else{
        str = "a";
      }
		// 出力
		System.out.println(str);     
	}
        
      }
}