n,k=map(int,input().split())
l1=list(map(int,input().split()))
l2=list(map(int,input().split()))
s1=set(l1)
s2=set(l2)
l3 = list(s1.union(s2))
l3.sort();
for j in (l3):
    print(j,end=' ')
print()
l4 = list(s1.intersection(s2))
l4.sort();
for i in (l4):
    print(i,end=' ')
/**************************************************************
	Problem: 1471
	User: admin
	Language: Python
	Result: Accepted
	Time:185 ms
	Memory:34480 kb
****************************************************************/