import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 文字の入力
		char c = sc.next().charAt(0);;
		// 出力
      	int ascii;
      	ascii = (int)c;

        if(ascii>=65 && 90>=ascii) 
          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