Ha, Wa = map(int, input().split())
Hb, Wb = map(int, input().split())
Hc, Wc = map(int, input().split())

data = []
data.append((Ha, Wa, 'A'))
data.append((Hb, Wb, 'B'))
data.append((Hc, Wc, 'C'))

data.sort(key=lambda x:x[1])
data.sort(key=lambda x:x[0], reverse=True)
#data.sort(key=lambda x: (-x[0], x[1]))
for _, _, s in data:
    print(s)