sa, na, _ = input().split()
sb, nb, _ = input().split()

n = len(na)
m = len(nb)
if n > m:
    print(sa)
elif n < m:
    print(sb)
else:
    for i in range(n):
        if int(na[i]) > int(nb[i]):
            print(sa)
            exit()
        elif int(na[i]) < int(nb[i]):
            print(sb)
            exit()
    print(-1)