import sys



readline = sys.stdin.readline

MOD = 10 ** 9 + 7

INF = float('INF')

sys.setrecursionlimit(10 ** 5)





def main():

    a = eval(input())



    if a == a.upper():

        print("A")

    else:

        print("a")





if __name__ == '__main__':

    main()

s = eval(input())



if s == s.upper():

    print("A")

else:

    print("a")
import sys

readline = sys.stdin.readline
MOD = 10**9 + 7
INF = float("INF")
sys.setrecursionlimit(10**5)


def main():
    a = eval(input())
    if a == a.upper():
        print("A")
    else:
        print("a")


if __name__ == "__main__":
    main()

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

-import sys - -readline = sys.stdin.readline -MOD = 10**9 + 7 -INF = float("INF") -sys.setrecursionlimit(10**5) - - -def main(): -    a = eval(input()) -    if a == a.upper(): -        print("A") -    else: -        print("a") - - -if __name__ == "__main__": -    main() +s = eval(input()) +if s == s.upper(): +    print("A") +else: +    print("a")