
import java.util.Map.Entry;
import java.util.*;
import java.math.*;
import org.w3c.dom.css.Counter;
  
public class Main{
    public static void main(final String[] args){
       
        final Scanner sc = new Scanner(System.in);
        //int N =sc.nextInt();
        //ArrayList<Integer>  allmen =new ArrayList <Integer>();
        //HashSet doubled =new HashSet<Integer>();
        String str = sc.next();
        if( Character.isUpperCase( str.charAt( 0 ) ) ) {
            System.out.println( "A" );
        }
        else {
            System.out.println( "a" );
        }
        //System.out.println(ans);
    }
}
/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