#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define QwQ01AwA return 0

void solve() {
	int n, m;
	cin >> n >> m;
	if (n < m) swap(n, m);
	string s;
	cin >> s;
	vector <int> ans1, ans2;
	vector <int> pos(n + m + 1, -1);
	vector <int> sum(n + m, 0);
	int cnt = 0;
	for (int i = 0; i < n + m; i++) {
		if (i) sum[i] = sum[i - 1];
		if (s[i] == '0') sum[i]++;
		else cnt++, pos[cnt] = i;
	}
	for (int i = 0, j = 0; i < n + m; i++) {
		if (ans1.size() == n) ans2.push_back(s[i] - '0');
		else if (ans2.size() == m) ans1.push_back(s[i] - '0');
		else if (s[i] == '0') ans2.push_back(0);
		else {
			j++;
			int d = ans2.size() + n - m - ans1.size() + 1;
			if (j + d > cnt) {
				ans1.push_back(1);
				continue;
			}
			int r = pos[j + d];
			int dis = sum[r] - sum[i];
			if (dis > m - ans2.size() - 1) {
				ans1.push_back(1);
				continue;
			}
			ans2.push_back(1);
		}
	}
	// print
	reverse(ans1.begin(), ans1.end());
	reverse(ans2.begin(), ans2.end());
	while (!ans1.empty() && ans1.back() == 0) ans1.pop_back();
	while (!ans2.empty() && ans2.back() == 0) ans2.pop_back();
	if (ans1.size() < ans2.size()) swap(ans1, ans2);
	if (ans1.empty()) {
		cout << 0 << '\n';
		return ;
	}
	int add = 0;
	for (int i = 0; i < (int)ans2.size(); i++) {
		ans1[i] += ans2[i] + add;
		if (ans1[i] >= 2) ans1[i] -= 2, add = 1;
		else add = 0;
	}
	for (int i = ans2.size(); i < (int)ans1.size(); i++) {
		ans1[i] += add;
		if (ans1[i] >= 2) ans1[i] -= 2, add = 1;
		else add = 0;
	}
	if (add) cout << 1;
	for (int i = (int)ans1.size() - 1; i >= 0; i--) cout << ans1[i];
	cout << '\n';
}

void file() {
	freopen("partition.in", "r", stdin);
	freopen("partition.out", "w", stdout);
}

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	int t;
	cin >> t;
	while (t--) solve();
	QwQ01AwA;
}