import java.util.*;
import java.io.*;
class Main
{
    public static void main(String args[])throws IOException
    {
        char ch;
        ch=(char)System.in.read();
        if(Character.isUpperCase(ch))
            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