#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define vec vector
using namespace std;
 
int main() {
	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	#ifdef LOCAL
//		freopen("in1.txt", "r", stdin);
//		freopen("in1.txt", "w", stdout);
	#endif
	int tt;
	cin >> tt;
	while (tt--) {
		int n;
		cin >> n;
		vec<string> a(3);
		vec<int> b(3), c(3);
		for (int i=0; i<3; i++) {
			cin >> a[i];
			for (int l=0; l<2*n; l++) {
				b[i] += (a[i][l] == '0');
				c[i] += (a[i][l] == '1');
			}
		}
		int p = -1, q, r;
		for (int i=0; i<3 && p==-1; i++) {
			for (int j=0; j<3 && p==-1; j++) {
				if (i == j) continue;
				if (b[i]>=n && b[j]>=n) {
					p = i;
					q = j;
					r = 0;
				}
				if (c[i]>=n && c[j]>=n) {
					p = i;
					q = j;
					r = 1;
				}
			}
		}
		assert(p != -1);
		
//		cout << p << ' ' << q << '\n';
		for (int i=0, j=0; i<2*n || j<2*n;) {
			if (i == 2*n) {
				while (j<2*n) cout << a[q][j++];
				break;
			}
			if (j == 2*n) {
				while (i<2*n) cout << a[p][i++];
				break;
			}
			
			while (i<2*n && a[p][i]-'0' != r) cout << a[p][i++];
			while (j<2*n && a[q][j]-'0' != r) cout << a[q][j++];
			if (i<2*n && j<2*n) {
				cout << a[p][i];
				i++;
				j++;
			}
		}
		cout << '\n';
	}
}