import java.util.*;
import java.lang.*;
 
class Main{
	public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
    char line = sc.next().toCharArray()[0];
    if(Character.isLowerCase(line)){
    	System.out.println("a");
    	}
      else {
      	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