import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Arrays;
import java.util.Collections;
import java.util.*;
class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    String a = scan.next();
    String[] al = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
    for (int i = 0;i < 26;i++) {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    }
    System.out.println("A");
  }
} import java.util.Scanner; Scanner java.util import java.util.List; List java.util import java.util.ArrayList; ArrayList java.util import java.util.Comparator; Comparator java.util import java.util.Arrays; Arrays java.util import java.util.Collections; Collections java.util import java.util.*; util.* java class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    String a = scan.next();
    String[] al = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
    for (int i = 0;i < 26;i++) {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    }
    System.out.println("A");
  }
} Main public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    String a = scan.next();
    String[] al = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
    for (int i = 0;i < 26;i++) {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    }
    System.out.println("A");
  } main {
    Scanner scan = new Scanner(System.in);
    String a = scan.next();
    String[] al = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
    for (int i = 0;i < 26;i++) {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    }
    System.out.println("A");
  } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) String a = scan.next(); a scan.next() scan.next scan String[] al = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"}; al {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"} "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" for (int i = 0;i < 26;i++) {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    } int i = 0; int i = 0; i 0 i < 26 i 26 i++ i++ i {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    } {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    } if (a.equals(al[i])) {
        System.out.println("a");
        return;
      } a.equals(al[i]) a.equals a al[i] al i {
        System.out.println("a");
        return;
      } System.out.println("a") System.out.println System.out System System.out "a" return; System.out.println("A") System.out.println System.out System System.out "A" String[] args args
import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Arrays;
import java.util.Collections;
import java.util.*;
class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    String a = scan.next();
    String[] al = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
    for (int i = 0;i < 26;i++) {
      if (a.equals(al[i])) {
        System.out.println("a");
        return;
      }  
    }
    System.out.println("A");
  }
}
