#include <bits/stdc++.h>
#define N 2000010
using namespace std;
int T, n, m, ca, cb, cd;
int a[N], b[N], c[N], d[N];
char s[N];
void run(int n, int m) {
    for(int i = 1; i <= n + m + 10; i++) a[i] = b[i] = c[i] = 0;
    ca = 0, cb = 0;
    for(int i = 1; i <= n + m; i++) {
        if(ca == n) b[++cb] = s[i] - '0';
        else if(cb == m) a[++ca] = s[i] - '0';
        else if(s[i] == '0') b[++cb] = s[i] - '0';
        else if(s[i] == '1') a[++ca] = s[i] - '0';
    }
    reverse(a + 1, a + ca + 1);
    reverse(b + 1, b + cb + 1);
    int cc = max(ca, cb);
    for(int i = 1; i <= cc; i++) {
        c[i] = a[i] + b[i];
        if(c[i] >= 2) {
            c[i + 1] += c[i] / 2;
            if(i + 1 > cc) cc = i + 1;
            c[i] %= 2;
        }
    }
    while(c[cc] == 0 && cc > 1) cc--;
    reverse(c + 1, c + cc + 1);
    if(cc > cd) {
        cd = cc;
        for(int i = 1; i <= cd; i++) d[i] = c[i];
    } else if(cc == cd) {
        for(int i = 1; i <= cd; i++) {
            if(c[i] < d[i]) break;
            if(c[i] > d[i]) {
                for(int j = 1; j <= cd; j++) d[j] = c[j];
                break;
            }
        }
    }
}
void solve() {
    for(int i = 1; i <= n + m + 10; i++) d[i] = 0;
    cd = 1;
    scanf("%d%d%s", &n, &m, s + 1);
    run(n, m);
    run(m, n);
    for(int i = 1; i <= cd; i++) printf("%d", d[i]);
    printf("\n");
}
int main() {
    // freopen("example2.in", "r", stdin);
    // freopen("partition.out", "w", stdout);
    scanf("%d", &T);
    while(T--) solve();
}