import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.nextLine();
        if(a.equals("a") || a.equals("b") || a.equals("c") || a.equals("d") || a.equals("e") || a.equals("f") || a.equals("g") || a.equals("h") || a.equals("i") || a.equals("j")
        || a.equals("k") || a.equals("l") || a.equals("m") || a.equals("n") || a.equals("o") || a.equals("p") || a.equals("q") || a.equals("r") || a.equals("s") || a.equals("t")
        || a.equals("u") || a.equals("v") || a.equals("w") || a.equals("x") || a.equals("y") || a.equals("z"))
        System.out.println("a");
        else if(a.equals("A") || a.equals("B") || a.equals("C") || a.equals("D") || a.equals("E") || a.equals("F") || a.equals("G") || a.equals("H") || a.equals("I") || a.equals("J")
        || a.equals("K") || a.equals("L") || a.equals("M") || a.equals("N") || a.equals("O") || a.equals("P") || a.equals("Q") || a.equals("R") || a.equals("S") || a.equals("T")
        || a.equals("U") || a.equals("V") || a.equals("W") || a.equals("X") || a.equals("Y") || a.equals("Z"))
        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