import java.io.*;

class Main
{
    public static void main(String[] args) throws IOException
    {
        BufferedReader alpha = 
         new BufferedReader(new InputStreamReader(System.in));
        
        String a = alpha.readLine();

        if(a == a.toUpperCase()){
            System.out.print("A");
        } else if(a == a.toLowerCase()){
            System.out.print("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