# Read the input lines for both players
a = input().split()
b = input().split()

sa, pa, xa = a
sb, pb, xb = b

# Compare the lengths first
if len(pa) > len(pb):
    print(sa)
elif len(pa) < len(pb):
    print(sb)
else:
    # If lengths are equal, perform lexicographical comparison
    if pa > pb:
        print(sa)
    elif pa < pb:
        print(sb)
    else:
        print(-1)