"""
author @ Mobarak Hosen Shakil
Dept. of ICE, Islamic University
Kushtia, Bangladesh
File Name: toph.py
Created on: 2:57 PM, 10 - 02 - 2019
"""
n, m = map(int, input().split())
s1 = list(map(int, input().split()))
s2 = list(map(int, input().split()))
p1 = set(s1)
p2 = set(s2)
ans = p1 | p2
res = list(ans)
res.sort()
for x in res:
print(x, ' ', end="")
IiIiCmF1dGhvciBAIE1vYmFyYWsgSG9zZW4gU2hha2lsCkRlcHQuIG9mIElDRSwgSXNsYW1pYyBVbml2ZXJzaXR5Ckt1c2h0aWEsIEJhbmdsYWRlc2gKCkZpbGUgTmFtZTogdG9waC5weQpDcmVhdGVkIG9uOiAyOjU3IFBNLCAxMCAtIDAyIC0gMjAxOSAKCiIiIgoKbiwgbSA9IG1hcChpbnQsIGlucHV0KCkuc3BsaXQoKSkKCnMxID0gbGlzdChtYXAoaW50LCBpbnB1dCgpLnNwbGl0KCkpKQpzMiA9IGxpc3QobWFwKGludCwgaW5wdXQoKS5zcGxpdCgpKSkKCnAxID0gc2V0KHMxKQpwMiA9IHNldChzMikKCmFucyA9IHAxIHwgcDIKcmVzID0gbGlzdChhbnMpCnJlcy5zb3J0KCkKCmZvciB4IGluIHJlczoKICAgIHByaW50KHgsICcgJywgZW5kPSIiKQo=