h1, w1 = map(int, input().split())
h2, w2 = map(int, input().split())
h3, w3 = map(int, input().split())
rec = []
rec.append(("A", h1, w1))
rec.append(("B", h2, w2))
rec.append(("C", h3, w3))

rec = sorted(rec, key=lambda s: s[2])
rec = sorted(rec, key=lambda s: s[1], reverse=True)
for i in rec:
    print(i[0])