import sys



sys.setrecursionlimit(10 ** 8)



input = sys.stdin.readline





def main():

    S = input().strip()



    if ord('A') <= ord(S[0]) <= ord('Z'):

        print("A")

    else:

        print("a")





if __name__ == '__main__':

    main()



import sys



sys.setrecursionlimit(10 ** 8)



input = sys.stdin.readline





def main():

    S = input().strip()



    if S.islower():

        print("a")

    else:

        print("A")







if __name__ == '__main__':

    main()



import sys

sys.setrecursionlimit(10**8)
input = sys.stdin.readline


def main():
    S = input().strip()
    if ord("A") <= ord(S[0]) <= ord("Z"):
        print("A")
    else:
        print("a")


if __name__ == "__main__":
    main()

import sys

sys.setrecursionlimit(10**8)
input = sys.stdin.readline


def main():
    S = input().strip()
    if S.islower():
        print("a")
    else:
        print("A")


if __name__ == "__main__":
    main()

-    if ord("A") <= ord(S[0]) <= ord("Z"): +    if S.islower(): +        print("a") +    else: -    else: -        print("a")