import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        char alpha = br.readLine().charAt(0);

        if (alpha > 96) {
            bw.write("a\n");
        } else {
            bw.write("A\n");
        }

        bw.close();
        br.close();
    }
}

/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