import java.util.*;

class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    char ch = sc.next().toCharArray()[0];
    char a = 'a';
    Set<Character> set = new HashSet<>();
    for(int i=0;i<26;i++){
      set.add((char)(a+i));
    }
    if(set.contains(ch)){
      System.out.println('a');
    }else{
      System.out.println('A');
    }
    
  }
} import java.util.*; util.* java class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    char ch = sc.next().toCharArray()[0];
    char a = 'a';
    Set<Character> set = new HashSet<>();
    for(int i=0;i<26;i++){
      set.add((char)(a+i));
    }
    if(set.contains(ch)){
      System.out.println('a');
    }else{
      System.out.println('A');
    }
    
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    char ch = sc.next().toCharArray()[0];
    char a = 'a';
    Set<Character> set = new HashSet<>();
    for(int i=0;i<26;i++){
      set.add((char)(a+i));
    }
    if(set.contains(ch)){
      System.out.println('a');
    }else{
      System.out.println('A');
    }
    
  } main {
    Scanner sc = new Scanner(System.in);
    char ch = sc.next().toCharArray()[0];
    char a = 'a';
    Set<Character> set = new HashSet<>();
    for(int i=0;i<26;i++){
      set.add((char)(a+i));
    }
    if(set.contains(ch)){
      System.out.println('a');
    }else{
      System.out.println('A');
    }
    
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) char ch = sc.next().toCharArray()[0]; ch sc.next().toCharArray()[0] sc.next().toCharArray() sc.next().toCharArray sc.next() sc.next sc 0 char a = 'a'; a 'a' Set<Character> set = new HashSet<>(); set new HashSet<>() for(int i=0;i<26;i++){
      set.add((char)(a+i));
    } int i=0; int i=0; i 0 i<26 i 26 i++ i++ i {
      set.add((char)(a+i));
    } {
      set.add((char)(a+i));
    } set.add((char)(a+i)) set.add set (char)(a+i) a i if(set.contains(ch)){
      System.out.println('a');
    }else{
      System.out.println('A');
    } set.contains(ch) set.contains set ch {
      System.out.println('a');
    } System.out.println('a') System.out.println System.out System System.out 'a' {
      System.out.println('A');
    } System.out.println('A') System.out.println System.out System System.out 'A' String[] args args
import java.util.*;

class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    char ch = sc.next().toCharArray()[0];
    char a = 'a';
    Set<Character> set = new HashSet<>();
    for(int i=0;i<26;i++){
      set.add((char)(a+i));
    }
    if(set.contains(ch)){
      System.out.println('a');
    }else{
      System.out.println('A');
    }
    
  }
}