bool M1;
#include<bits/stdc++.h>
#define look_memory cerr<<abs(&M2-&M1)/1024.0/1024<<'\n'
#define look_time cerr<<(clock()-ST)*1.0/CLOCKS_PER_SEC<<'\n'
//#define int long long
using namespace std;
const int N=1000005;
int T0,n,m;
string s;
int a[N];
/*
inline int qpow(int x,int p){
	int res=1;
	while(p){
		if(p&1) res=res*x;
		x=x*x;
		p>>=1;
	}
	return res;
}
void to2(int x){
	if(!x){cout<<0<<'\n';return;} 
	int q[21],tq=0;
	while(x){
		if(x&1) q[++tq]=1;
		else q[++tq]=0;
		x>>=1;
	}
	for(int i=tq;i>=1;i--) cout<<q[i];
	cout<<'\n';
}
int f[505][505];//A:pick-j
void solve1(){
	for(int i=1;i<=n+m+1;i++) for(int j=0;j<=n;j++) f[i][j]=0;
	for(int i=n+m,iq=1;i>=1;i--,iq++){
		for(int j=0;j<=min(n,iq);j++){
			if(a[i]){
				if(j==0) f[i][j]=f[i+1][j]+qpow(2,iq-1);
				else{
					if(j==iq) f[i][j]=f[i+1][j-1]+qpow(2,j-1);
					else f[i][j]=max(f[i+1][j]+qpow(2,iq-j-1),f[i+1][j-1]+qpow(2,j-1));
				}
			}else{
				if(j==0) f[i][j]=f[i+1][j];
				else f[i][j]=max(f[i+1][j],f[i+1][j-1]);
			}
		}
	}
	to2(f[1][n]);
//	cout<<f[1][n]<<'\n';
}
*/
int rt[2005][2005];
const int N2=5e7;
int R;
int fn[4005],tf,hv1;
struct segtree{
	struct node{
		int ls,rs,t,h;
	}c[N2+5];
	int tot;
	void mdf(int l,int r,int &p,int p0,int x){//使用时整体偏移了一位，2^0-->2^1 
		c[p=++tot]=c[p0];
		c[p].t++;
		if(l==r) return;
		int mid=l+r>>1;
		if(x<=mid) mdf(l,mid,c[p].ls,c[p0].ls,x);
		else mdf(mid+1,r,c[p].rs,c[p0].rs,x);
	}
	int qry(int l,int r,int px,int py,int dtx,int dty){
		if(l==r){
			int xx=c[px].t;
			if(dtx==l) xx++;
			int yy=c[py].t;
			if(dty==l) yy++;
			if(xx<yy) return 0;
			if(xx==yy) return 1;
			return 2;
		}
		int mid=l+r>>1;
		if(dtx<=mid && dty<=mid && c[c[px].rs].t==0 && c[c[py].rs].t==0)
			return qry(l,mid,c[px].ls,c[py].ls,dtx,dty);
		int cmp=qry(mid+1,r,c[px].rs,c[py].rs,dtx,dty);
		if(cmp!=1) return cmp;
		int cmpl=qry(l,mid,c[px].ls,c[py].ls,dtx,dty);
		return cmpl;
	}
	void jw(int l,int r,int p){
		if(l==r){
			fn[++tf]=c[p].t;
			if(c[p].t) hv1=1;
			return;
		}
		int mid=l+r>>1;
		jw(l,mid,c[p].ls);
		jw(mid+1,r,c[p].rs);
	}
}T;
void clean(){
	for(int i=1;i<=n+m+1;i++) for(int j=0;j<=n;j++) rt[i][j]=0;
	for(int i=0;i<=T.tot;i++) T.c[i].ls=T.c[i].rs=T.c[i].t=0;
	T.tot=0;
}
void solve2(){
//	for(int i=1;i<=n+m;i++) for(int j=0;j<=n;j++) rt[i][j]=++tot;
//	clear! T.tot=0;
	for(int i=n+m,iq=1;i>=1;i--,iq++){
		int lim=min(n,iq);
		for(int j=0;j<=lim;j++){
			if(a[i]){
				if(j==0) T.mdf(1,R,rt[i][j],rt[i+1][j],iq);
				else{
					if(j==iq) T.mdf(1,R,rt[i][j],rt[i+1][j-1],j);
					else{//left更大 return 12 
						int cmp=T.qry(1,R,rt[i+1][j],rt[i+1][j-1],iq-j,j);
						if(cmp>=1) T.mdf(1,R,rt[i][j],rt[i+1][j],iq-j);
						else T.mdf(1,R,rt[i][j],rt[i+1][j-1],j);
					}
				}
			}else{
				if(j==0) rt[i][j]=rt[i+1][j];
				else{
					int cmp=T.qry(1,R,rt[i+1][j],rt[i+1][j-1],0,0);
					if(cmp>=1) rt[i][j]=rt[i+1][j];
					else rt[i][j]=rt[i+1][j-1];
				}
			}
		}
	}
	hv1=0,tf=0;
	T.jw(1,R,rt[1][n]);
	if(hv1==0){
		cout<<"0\n";
		clean();
		return;
	}
	for(int i=1;i<=tf;i++){
		if(fn[i]==0||fn[i]==1) continue;
		fn[i+1]+=fn[i]/2;
		fn[i]=(fn[i]&1);
	}
	int num=fn[tf+1];
	while(num){
		fn[++tf]=(num&1);
		num/=2;
	}
	bool prex=0;
	for(int i=tf;i>=1;i--){
		if(fn[i]){
			prex=1;
			cout<<1;
		}else if(prex){
			cout<<0; 
		}
	}
	cout<<'\n';
	clean();
}
/*
1
6 4
1110001011
*/
bool M2;
signed main(){
//	fc example2.out partition.out
//	look_memory;
//	freopen("example2.in","r",stdin);
//	freopen("partition.out","w",stdout);
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>T0;
	while(T0--){
		cin>>n>>m>>s;
		if(n<m) swap(n,m);
		s="#"+s;
		for(int i=1;i<=n+m;i++) a[i]=(s[i]=='1');
//		if(n<=10&&m<=10){solve1();continue;}
		if(n<=500&&m<=500){R=500;solve2();continue;}
		if(n<=2000&&m<=2000){R=n+m;solve2();continue;}
	}
	return 0;
}
/*
3
1 3
0110
3 3
100011
1 2
000

110
111
0
*/