A = eval(input())



if A == A.upper():

    print('A')

else:

    print('a')

A = eval(input())



if A.isupper():

    print('A')

else:

    print('a')

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

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

-if A == A.upper(): +if A.isupper():