ha,wa=map(int,input().split())
hb,wb=map(int,input().split())
hc,wc=map(int,input().split())

from operator import index, itemgetter

l=[[ha,wa],[hb,wb],[hc,wc]]

l2=sorted(l,key=lambda x: (x[0],-x[1]))
l2=l2[::-1]

for x in l2:
    if l.index(x)==0:
        print("A")
    elif l.index(x)==1:
        print("B")
    elif l.index(x)==2:
        print("C")