import sys
readline=sys.stdin.readline

lst=[]
h,w=map(int,readline().split())
lst.append((-h,w,"A"))
h,w=map(int,readline().split())
lst.append((-h,w,"B"))
h,w=map(int,readline().split())
lst.append((-h,w,"C"))
lst.sort()
for tpl in lst:
    print(tpl[2])