hw_list = []

h, w = map(int, (input().split()))
hw_list.append(['A', h, w])

h, w = map(int, (input().split()))
hw_list.append(['B', h, w])

h, w = map(int, (input().split()))
hw_list.append(['C', h, w])

hw_list = sorted(hw_list, key=lambda x:(-x[1],x[2]))

for hw in hw_list:
    print(hw[0])