/*
    written by Pankaj Kumar.
    country:-INDIA
    Institute: National Institute of Technology, Uttarakhand
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll ;
typedef unsigned long long ull;
typedef vector<ll> vl;
#define speed cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(0);
/*  Abbrevations  */
#define ff first
#define ss second
#define mp make_pair
#define line cout<<endl;
#define pb push_back
#define Endl "\n"
// loops
#define forin(arr,n) for(ll i=0;i<n;i++) cin>>arr[i];
// Some print
#define no cout<<"No"<<endl;
#define yes cout<<"Yes"<<endl;
// sort
#define all(V) (V).begin(),(V).end()
#define srt(V) sort(all(V))
#define srtGreat(V) sort(all(V),greater<ll>())
// some extra
#define printv(v) for(ll i=0;i<ll(v.size());i++){cout<<v[i]<<" ";} line;
#define precision(x) cout<<fixed<<setprecision(x);
#define sz(V) ll(V.size())
// template
template <typename T>
T mymax(T x,T y)
{
    return (x>y)?x:y;
}
// function
ll power(ll x,ll y,ll mod)
{
    ll res=1;
    // x=x%mod;
    while(y>0)
    {
        if(y%2==1)
        {
            res*=x;
            // res=res%mod;
        }
        y/=2; x*=x; // x=x%mod;
    }
    return res;
}
ll str_to_num(string s)
{
    return stoi(s);
}

string num_to_str(ll num)
{
    return to_string(num);
}
// datatype definination
#define ordered_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
class Point
{
    public:
        ll x;
        ll y;
        ll z;
        ll getsum()
        {
            return x+y+z;
        }
};
/* ascii value 
A=65,Z=90,a=97,z=122
*/
/*  --------------------MAIN PROGRAM----------------------------*/
// to run ctrl+b
const ll INF=LONG_MAX;
const ll mod1=1e9+7;
const ll mod2=998244353;


// Techniques
// divide into cases, brute force, pattern finding
// sort, greedy, binary search, two pointer
// transform into graph

ll solve()
{
    ll n,m;
    cin>>n>>m;
    map<ll,ll> a,b;
    for(ll i=0;i<n;i++){
        ll temp;
        cin>>temp;
        a[temp]++;
    }
    for(ll i=0;i<m;i++){
        ll temp;
        cin>>temp;
        b[temp]++;
    }
    vl ans;
    for(auto x:a){
        if(b[x.ff]==0){
            ans.pb(x.ff);
        }
    }
    for(auto x:b){
        if(a[x.ff]==0){
            ans.pb(x.ff);
        }
    }
    srt(ans);
    printv(ans);
    return 0;
}

int main()
{
    speed;
    /* #ifndef ONLINE_JUDGE
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
    #endif */
    ll TestCase=1;
    // cin>>TestCase;
    while(TestCase--)
    {
        solve();
    }
}
/* -----------------END OF PROGRAM --------------------*/
/*
* stuff you should look before submission 
* constraint and time limit
* int overflow
* special test case (n=0||n=1||n=2)
* don't get stuck on one approach if you get wrong answer
*/
#include <bits/stdc++.h>
using namespace std;
/* ループ処理 0からnまで*/
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main()
{
  int N, M;
  cin >> N >> M;
  std::vector<int> v = {};
  rep(i, N)
  {
    int temp;
    cin >> temp;
    v.push_back(temp);
  }
  rep(j, M)
  {
    int temp;
    cin >> temp;
    auto itr = std::find(v.begin(), v.end(), temp);
    if (itr != v.end())
    {
      v.erase(itr);
    }
    else
    {
      v.push_back(temp);
    }
  }
  std::sort(v.begin(), v.end());
  std::size_t size = v.size();
  rep(k, (int)size)
  {
    cout << v[k];
    if (k != (int)size - 1)
    {
      cout << ' ';
    }
  }
  cout << endl;
}