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]), reverse=True)

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