#include<bits/stdc++.h>
#define eb emplace_back
#define mk(x,y) make_pair(x,y)
#define fi first
#define se second
using namespace std;
const int N=1000005;
int n,m,a[N],b[N],c[N],ans[N],LL,L;
string S;
void gt(int L){
	LL=L;
	for (int i=1;i<=LL;++i)ans[i]=c[i];
}
bool chk(int x){
	int o=n;
	for (int i=0;i<x;++i)a[o--]=S[i]-48;
	int u=n-x+1,v=m+1;
	for (int i=x;i<(int)S.size();++i){
		int o=S[i]-48;
		if (u==1){b[--v]=o;continue;}
		if (v==1){a[--u]=o;continue;}
		if (!o){
			if (u>v){
				b[--v]=o;
			}
			else{
				a[--u]=o;
			}
		}
		else{
			if (u>v){
				a[--u]=o;
			}
			else{
				b[--v]=o;
			}
		}
	}
	L=max(n,m)+1;
	for (int i=1;i<=max(n,m)+1;++i)c[i]=0;
	for (int i=1;i<=max(n,m)+1;++i){
		c[i]+=a[i]+b[i];
		c[i+1]+=c[i]/2;
		c[i]&=1;
	}
//	cout<<"\n";
//	cout<<x<<"\n";
//	for (int i=n;i;--i)cout<<a[i];cout<<"\n";
//	for (int i=m;i;--i)cout<<b[i];cout<<"\n";
//	cout<<"\n";
	while (c[L]==0&&L>1)--L;
	if (L>LL)gt(L);
	else if (L==LL){
		for (int i=L;i>=1;--i){
			if (c[i]>ans[i]){
				gt(L);
				break;
			}
			else if (c[i]<ans[i])break;
		}
	}
	int ck=0;
	for (int i=m;i;--i)
		if (b[i]==0){
			ck=i;break;
		}
	for (int i=1;i<=max(n,m)+1;++i)a[i]=b[i]=0;
	return !(ck<n-x);
}
void solve(){
	cin>>n>>m>>S;
	if (n>m)swap(n,m);
	LL=1;ans[LL]=0;
	int l=0,r=n;
	while (l<=r){
		int mid=(l+r)>>1;
		if (!chk(mid))l=mid+1;
		else r=mid-1;
	}
	for (int i=LL;i;--i)cout<<ans[i];cout<<"\n";
}
void init(){
	for (int i=0;i<=LL;++i)ans[i]=0;
	LL=0;
}
int main(){
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int T;
	cin>>T;
	while (T--)solve(),init();
}