import sys


def input(): return sys.stdin.readline().rstrip('\n')


def main():
    ha, wa = map(int, input().split())
    hb, wb = map(int, input().split())
    hc, wc = map(int, input().split())
    z = [(-ha, wa, 'A'), (-hb, wb, 'B'), (-hc, wc, 'C')]
    z.sort()
    for k in z:
        print(k[2])


if __name__ == '__main__':
    main()