#include <iostream>
#include <set> 
#include <iterator>
#include <bitset> 
#include <bits/stdc++.h> 
using namespace std;
typedef  long long int ll;
ll mod=1000000007;


int main() {
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        string s;
        for(int i=0;i<3;i++ )
        {
            cin>>s;
        }
        string ans;
        for(int i=0;i<n;i++)
            ans.push_back('0');
        
        
        for(int i=0;i<n;i++)
            ans.push_back('1');
            ans.push_back('0');
        cout<<ans<<endl;
        
        
        
    
        
    
        
    }
    return 0;
}

#pragma GCC optimize ("Ofast")
#pragma GCC optimization ("unroll-loops, no-stack-protector")
#pragma GCC target ("avx")
#pragma GCC target ("avx2")
#pragma GCC target ("fma")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define ll long long
#define ull unsigned long long
#define ld long double
#define pii pair <int, int>
#define pll pair <ll, ll>
#define pci pair <char, int>
#define pld pair <ld, ld>
#define ppld pair <pld, pld>
#define ppll pair <pll, pll>
#define pldl pair <ld, ll>
#define vll vector <ll>
#define vvll vector <vll>
#define vpll vector <pll>
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define mll map <ll, ll>
#define fastmap gp_hash_table
#define cd complex <double>
#define vcd vector <cd>
#define PI 3.14159265358979
#define ordered_set tree <ll, null_type, less <ll>, rb_tree_tag, tree_order_statistics_node_update>
#pragma 03
using namespace std;
using namespace __gnu_pbds;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
void solve(){
	ll n; cin >> n;
	string s1, s2, s3; cin >> s1 >> s2 >> s3;
	string ans; ans.resize(2 * n + 1);
	ans[0] = '1';
	for (ll i = 1; i <= n; i++) ans[i] = '0';
	for (ll i = n + 1; i <= 2 * n; i++) ans[i] = '1';
	cout << ans << "\n";
}
int main(){
	fastio;
	ll t; cin >> t;
	while (t--) solve();
}