#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;

#define REP(i, n) for (ll i = 0; i < n; i++)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, m, n) for (ll i = m; i < n; i++)
#define FORR(i, m, n) for (ll i = m; i >= n; i--)
#define REPO(i, n) for (ll i = 1; i <= n; i++)
#define ll long long
#define INF (ll)1 << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(), n.end()
#define MOD 1000000007
#define P pair<ll, ll>


int main(){
    ll t;
    cin >> t;
    REP(i, t){
        ll n;
        string a;
        cin >> n >> a >> a >> a;
        cout << 0;
        REP(i, n)cout << 1;
        REP(i, n)cout << 0;
        cout << endl;
    }
}
/*  -*- coding: utf-8 -*-
 *
 * a.cc: A - Long Common Subsequence
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;

/* typedef */

/* global variables */

char s[MAX_N * 2 + 4];

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    int n;
    scanf("%d", &n);

    for (int i = 0; i < 3; i++) scanf("%s", s);

    for (int i = 0; i < n; i++) putchar('0');
    for (int i = 0; i < n; i++) putchar('1');
    putchar('0'); putchar('\n');
  }
  return 0;
}
