//#define _GLIBCXX_DEBUG
//#include "atcoder/all"
//using namespace atcoder;
#include <bits/stdc++.h>
#define int long long
#define ll long long
using ull = unsigned long long;
using namespace std;
#define Dump(x)                             \
    if (dbg) {                              \
        cerr << #x << " = " << (x) << endl; \
    }
#define overload4(_1, _2, _3, _4, name, ...) name
#define FOR1(n) for (ll i = 0; i < (n); ++i)
#define FOR2(i, n) for (ll i = 0; i < (n); ++i)
#define FOR3(i, a, b) for (ll i = (a); i < (b); ++i)
#define FOR4(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__)
#define FORR(i, a, b) for (int i = (a); i <= (b); ++i)
#define bit(n, k) (((n) >> (k)) & 1) /*nのk bit目*/
namespace mydef {
const int INF = 1ll << 60;
const int MOD = 1e9 + 7;
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;
}
void Yes(bool flag = true) {
    if (flag)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
}
void No(bool flag = true) {
    Yes(!flag);
}
void YES(bool flag = true) {
    if (flag)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;
}
void NO(bool flag = true) {
    YES(!flag);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T& val) {
    std::fill((T*)array, (T*)(array + N), val);
}
bool dbg = true;
}  // namespace mydef
using namespace mydef;
#define pb push_back
//#define mp make_pair
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define all(v) (v).begin(), (v).end()
#define SZ(x) ((int)(x).size())
#define vi vector<int>
#define vvi vector<vector<int>>
#define vp vector<pair<int, int>>
#define vvp vector<vector<pair<int, int>>>
#define pi pair<int, int>
//#define P pair<int, int>
//#define V vector<int>
//#define S set<int>
#define asn ans

int T;

bool check(const string& S, const string& T) {
    //S > T;
    int N = S.size();
    int now = 0;
    for (int i = 0; i < T.size(); i++) {
        if (now >= N)
            return false;
        while (T[i] != S[now]) {
            now++;
            if (now >= N)
                return false;
        }
        now++;
    }
    return true;
}

void solve() {
    while (T--) {
        int N;
        cin >> N;
        string S[3];
        cin >> S[0] >> S[1] >> S[2];
        vector<string> T;
        for (int a = 0; a < 2; a++) {
            for (int b = 0; b < 2; b++) {
                string A, B;
                for (int i = 0; i < N; i++) {
                    A += (char)('0' + a);
                    B += (char)('0' + b);
                }
                T.emplace_back('0' + A + B);
                T.emplace_back('1' + A + B);
                T.emplace_back(A + '0' + B);
                T.emplace_back(A + '1' + B);
                T.emplace_back(A + B + '0');
                T.emplace_back(A + B + '1');
            }
        }
        for (int i = 0; i < 3; i++) {
            S[i] += S[i];
        }
        string ans;
        for (auto& s : T) {
            if (check(S[0], s) && check(S[1], s) && check(S[2], s)) {
                ans = s;
                break;
            }
        }
        cout << ans << endl;
    }
}

signed main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    cin >> T;

    solve();
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define yes cout<<"YES\n";
#define no cout<<"NO\n";
#define fl(n) for(int i=0;i<n;i++)
#define flo(n) for(int i=1;i<=n;i++)
#define mii map<int,int>
#define mci map<char,int>
#define V vector<int>
#define vp vector<pair<int,int>>
#define pb push_back
#define pp pair<int,int>
#define ff first
#define ss second
#define S set<int>
#define all(v) v.begin(),v.end()
#define gr greater<int>()
#define show2(a, b) cout<<a<<' '<<b<<endl;
#define show3(a, b, c) cout<<a<<' '<<b<<' '<<c<<endl;
const long long mod=1000000007;
const int N=4e5+5;
const long double PI=3.14159265358;
vector<vector<int>> adj;
bool v[N];
void dfs(int j){
	v[j]=true;
	for(auto u:adj[j]){
		if(!v[u]) dfs(u);
	}
}

int32_t main(){
    int t=1;
    //cin>>t;
	while(t--){
	int n,m;
	cin>>n>>m;
	mii mp;
	fl(n+2) mp[i]=0;
	//for(auto i:mp) cout<<i.ff<<"."<<i.ss<<endl;
	int a[n];
	fl(n) cin>>a[i];
	S s;
	fl(m) mp[a[i]]++;
	//for(auto i:mp) cout<<i.ff<<"."<<i.ss<<endl;
	fl(n+2){
	if(mp[i]==0){
	s.insert(i);}
	}
	auto it=s.begin();
	int ans=*it;
//	cout<<ans<<endl;
//	for(auto it=s.begin();it!=s.end();it++) cout<<*it<<'.';	
//	cout<<endl;
	for(int i=m;i<n;i++){
		mp[a[i]]++;
//		cout<<mp[a[i]]<<'.';
		mp[a[i-m]]--;
//		cout<<mp[a[i-m]]<<endl;
		if(mp[a[i-m]]==0)
		s.insert(a[i-m]);
		if(s.find(a[i])!=s.end()){
			s.erase(a[i]);
		}
		auto k=s.begin();
		ans=min(ans,*k);
//		cout<<*k<<endl;
	}
	cout<<ans;
}
	return 0;
	}