# put your python code here
a1, b1, a2, b2 = int(input()), int(input()), int(input()), int(input())
if a2 < a1:
if b2 < a1:
print('пустое множество')
elif b2 == a1:
print(b2)
elif a1 < b2 <= b1:
print(a1, b2)
elif b2 > b1:
print(a1, b1)
elif a2 == a1:
if b2 <= b1:
print(a2, b2)
else:
print(a2, b1)
elif a2 < b1:
if b2 <= b1:
print(a2, b2)
else:
print(a2, b1)
elif a2 == b1:
print(a2)
else:
print('пустое множество')
a1, b1, a2, b2 = int(input()), int(input()), int(input()), int(input())
if a2 < a1:
if b2 < a1:
print('пустое множество')
elif b2 == a1:
print(b2)
elif a1 < b2 <= b1:
print(a1, b2)
elif b2 > b1:
print(a1, b1)
elif a2 == a1:
if b2 <= b1:
print(a2, b2)
else:
print(a2, b1)
elif a2 < b1:
if b2 <= b1:
print(a2, b2)
else:
print(a2, b1)
elif a2 == b1:
print(a2)
else:
print('пустое множество')