#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define mp make_pair
#define si(x) int(x.size())
const int mod=998244353,MAX=200005,INF=1<<30;

int main(){
    
    std::ifstream in("text.txt");
    std::cin.rdbuf(in.rdbuf());
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int N,M;cin>>N>>M;
    vector<int> cnt(10000);
    for(int i=0;i<N;i++){
        int a;cin>>a;
        cnt[a]++;
    }
    
    for(int i=0;i<M;i++){
        int a;cin>>a;
        cnt[a]++;
    }
    
    for(int i=1;i<=1000;i++){
        if(cnt[i]==1) cout<<i<<" ";
    }
    cout<<endl;
}

#include <bits/stdc++.h>
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll I=1167167167167167167;
ll Q=1e9+7;
#define rep(i,a) for (ll i=0;i<a;i++)
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end());reverse(v.begin(),v.end());}
template<class T> void print_tate(vector<T> &v) {rep(i,v.size()) cout<<v[i]<<"\n";}
void yneos(bool a){if(a) cout<<"Yes"<<"\n"; else cout<<"No"<<"\n";}

//頑張る
int main() {
	ll N,M;
	cin>>N>>M;
	vector<ll> p(1001);
	rep(i,N){
		ll a;
		cin>>a;
		p[a]^=1;
	}
	rep(i,M){
		ll a;
		cin>>a;
		p[a]^=1;
	}
	rep(i,1001){
		if(p[i]==1) cout<<i<<" ";
	}
	cout<<endl;
}
