def main():

    import sys

    input = sys.stdin.readline

    a = input().rstrip()

    if a.isupper():

        print("A")

    else:

        print("a")



if __name__ == '__main__':

    main()
a = eval(input())

if a.isupper():

  print("A")

else:

  print("a")

def main():
    import sys

    input = sys.stdin.readline
    a = input().rstrip()
    if a.isupper():
        print("A")
    else:
        print("a")


if __name__ == "__main__":
    main()

a = eval(input())
if a.isupper():
    print("A")
else:
    print("a")

-def main(): -    import sys - -    input = sys.stdin.readline -    a = input().rstrip() -    if a.isupper(): -        print("A") -    else: -        print("a") - - -if __name__ == "__main__": -    main() +a = eval(input()) +if a.isupper(): +    print("A") +else: +    print("a")