import java.io.*;

public class Main{
	public static void main(String[] args){
      try{
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      String str = br.readLine();
      if(Character.isUpperCase(str.charAt( 0 ))){
      	System.out.println("A");
      }
      else{
        System.out.println("a");
      }
      }
      catch(IOException e){
      	System.out.println("a");
      }
    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz