
import java.io.*;
import java.util.*;
 
 
class Main{
   public static void main(String[] args) {
      FastScanner sc = new FastScanner();
      out = new PrintWriter(new BufferedOutputStream(System.out));
      String s = sc.next();
      if(isUpperCase(s)) {
        out.println("A");
      }else {
        out.println("a");
      }
      out.close();
   }
   
   public static boolean isUpperCase(String s)
   {
       for (int i=0; i<s.length(); i++)
       {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       }
       return true;
   }

     

   //-----------PrintWriter for faster output---------------------------------
   public static PrintWriter out;
      
   //-----------MyScanner class for faster input----------
   public static class FastScanner {
      BufferedReader br;
      StringTokenizer st;
 
      public FastScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }
 
      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
 
      int nextInt() {
          return Integer.parseInt(next());
      }
 
      long nextLong() {
          return Long.parseLong(next());
      }
 
      double nextDouble() {
          return Double.parseDouble(next());
      }
 
      String nextLine(){
          String str = "";
      try {
         str = br.readLine();
      } catch (IOException e) {
         e.printStackTrace();
      }
      return str;
      }

   }
} import java.io.*; io.* java import java.util.*; util.* java class Main{
   public static void main(String[] args) {
      FastScanner sc = new FastScanner();
      out = new PrintWriter(new BufferedOutputStream(System.out));
      String s = sc.next();
      if(isUpperCase(s)) {
        out.println("A");
      }else {
        out.println("a");
      }
      out.close();
   }
   
   public static boolean isUpperCase(String s)
   {
       for (int i=0; i<s.length(); i++)
       {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       }
       return true;
   }

     

   //-----------PrintWriter for faster output---------------------------------
   public static PrintWriter out;
      
   //-----------MyScanner class for faster input----------
   public static class FastScanner {
      BufferedReader br;
      StringTokenizer st;
 
      public FastScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }
 
      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
 
      int nextInt() {
          return Integer.parseInt(next());
      }
 
      long nextLong() {
          return Long.parseLong(next());
      }
 
      double nextDouble() {
          return Double.parseDouble(next());
      }
 
      String nextLine(){
          String str = "";
      try {
         str = br.readLine();
      } catch (IOException e) {
         e.printStackTrace();
      }
      return str;
      }

   }
} Main //-----------PrintWriter for faster output---------------------------------
   public static PrintWriter out; out public static void main(String[] args) {
      FastScanner sc = new FastScanner();
      out = new PrintWriter(new BufferedOutputStream(System.out));
      String s = sc.next();
      if(isUpperCase(s)) {
        out.println("A");
      }else {
        out.println("a");
      }
      out.close();
   } main {
      FastScanner sc = new FastScanner();
      out = new PrintWriter(new BufferedOutputStream(System.out));
      String s = sc.next();
      if(isUpperCase(s)) {
        out.println("A");
      }else {
        out.println("a");
      }
      out.close();
   } FastScanner sc = new FastScanner(); sc new FastScanner() out = new PrintWriter(new BufferedOutputStream(System.out)) out new PrintWriter(new BufferedOutputStream(System.out)) String s = sc.next(); s sc.next() sc.next sc if(isUpperCase(s)) {
        out.println("A");
      }else {
        out.println("a");
      } isUpperCase(s) isUpperCase s {
        out.println("A");
      } out.println("A") out.println out "A" {
        out.println("a");
      } out.println("a") out.println out "a" out.close() out.close out String[] args args public static boolean isUpperCase(String s)
   {
       for (int i=0; i<s.length(); i++)
       {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       }
       return true;
   } isUpperCase {
       for (int i=0; i<s.length(); i++)
       {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       }
       return true;
   } for (int i=0; i<s.length(); i++)
       {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       } int i=0; int i=0; i 0 i<s.length() i s.length() s.length s i++ i++ i {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       } {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       } if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           } !Character.isUpperCase(s.charAt(i)) Character.isUpperCase(s.charAt(i)) Character.isUpperCase Character s.charAt(i) s.charAt s i {
               return false;
           } return false; false return true; true String s s public static class FastScanner {
      BufferedReader br;
      StringTokenizer st;
 
      public FastScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }
 
      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
 
      int nextInt() {
          return Integer.parseInt(next());
      }
 
      long nextLong() {
          return Long.parseLong(next());
      }
 
      double nextDouble() {
          return Double.parseDouble(next());
      }
 
      String nextLine(){
          String str = "";
      try {
         str = br.readLine();
      } catch (IOException e) {
         e.printStackTrace();
      }
      return str;
      }

   } FastScanner BufferedReader br; br StringTokenizer st; st public FastScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      } FastScanner {
         br = new BufferedReader(new InputStreamReader(System.in));
      } br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      } next {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      } while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          } st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          } try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              } catch (IOException e) {
                  e.printStackTrace();
              } IOException e {
                  e.printStackTrace();
              } e.printStackTrace() e.printStackTrace e {
                  st = new StringTokenizer(br.readLine());
              } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
          return Integer.parseInt(next());
      } nextInt {
          return Integer.parseInt(next());
      } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() {
          return Long.parseLong(next());
      } nextLong {
          return Long.parseLong(next());
      } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() {
          return Double.parseDouble(next());
      } nextDouble {
          return Double.parseDouble(next());
      } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine(){
          String str = "";
      try {
         str = br.readLine();
      } catch (IOException e) {
         e.printStackTrace();
      }
      return str;
      } nextLine {
          String str = "";
      try {
         str = br.readLine();
      } catch (IOException e) {
         e.printStackTrace();
      }
      return str;
      } String str = ""; str "" try {
         str = br.readLine();
      } catch (IOException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      } IOException e {
         e.printStackTrace();
      } e.printStackTrace() e.printStackTrace e {
         str = br.readLine();
      } str = br.readLine() str br.readLine() br.readLine br return str; str

import java.io.*;
import java.util.*;
 
 
class Main{
   public static void main(String[] args) {
      FastScanner sc = new FastScanner();
      out = new PrintWriter(new BufferedOutputStream(System.out));
      String s = sc.next();
      if(isUpperCase(s)) {
        out.println("A");
      }else {
        out.println("a");
      }
      out.close();
   }
   
   public static boolean isUpperCase(String s)
   {
       for (int i=0; i<s.length(); i++)
       {
           if (!Character.isUpperCase(s.charAt(i)))
           {
               return false;
           }
       }
       return true;
   }

     

   //-----------PrintWriter for faster output---------------------------------
   public static PrintWriter out;
      
   //-----------MyScanner class for faster input----------
   public static class FastScanner {
      BufferedReader br;
      StringTokenizer st;
 
      public FastScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }
 
      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }
 
      int nextInt() {
          return Integer.parseInt(next());
      }
 
      long nextLong() {
          return Long.parseLong(next());
      }
 
      double nextDouble() {
          return Double.parseDouble(next());
      }
 
      String nextLine(){
          String str = "";
      try {
         str = br.readLine();
      } catch (IOException e) {
         e.printStackTrace();
      }
      return str;
      }

   }
}
