# No.570 3人兄弟（その１）
ha, hb, hc = [int(input()) for i in range(3)]
h = [ha, hb, hc]

list.sort(h, reverse=True)

for i in range(3):
    if h[i] == ha:
        print('A')
    elif h[i] == hb:
        print('B')
    else:
        print('C')