x,y,z=map(int,input().split())
a,b,c=map(int,input().split())
if a >= x and b >= y and c >=z:
print("A")
elif a*2 >= x and b >= y and c >= z:
print("B")
elif b >= y and c >= z:
print("C")
elif b*2 >= y and c >= z:
print("D")
else:
print("E")