import string

alpha = string.ascii_uppercase

while True:
	datas = raw_input()

	x, y, z = map(lambda x: x.upper(), datas)

	p = alpha.index(y) - (alpha.index(x)+1)
	q = alpha.index(z) - (alpha.index(y)+1)

	print z if p > q else x
# print 'a' if (ord(datas[1].upper()) - ord(datas[0].upper())) > (ord(datas[1].upper()) - ord(datas[2].upper())) else 'b'