#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define bll __int128
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define fi first
#define sec second
#define vii vector<int>
#define pll pair<ll,ll>
#define vll vector<ll>
#define pii pair<int,int>
#define pil pair<int,ll>
#define re register
#define puu pair<ull,ull>
#define clr clear
#define vpi vector<pii>
#define qii queue<int>
using namespace std;
namespace io{
	const int __SIZE=(1<<22)+1;
	char ibuf[__SIZE],*iS,*iT,obuf[__SIZE],*oS=obuf,*oT=oS+__SIZE-1,__c,qu[55];int __f,qr,_eof;
#define Gc()(iS==iT?(iT=(iS=ibuf)+fread(ibuf,1,__SIZE,stdin),(iS==iT?EOF:*iS++)):*iS++)
	inline void flush(){fwrite(obuf,1,oS-obuf,stdout),oS=obuf;}
	inline void gc(char&x){x=Gc();}
	inline void pc(char x){*oS++=x;if(oS==oT)flush();}
	inline void pstr(const char*s){int __len=strlen(s);for(__f=0;__f<__len;++__f)pc(s[__f]);}
	inline void gstr(char*s){for(__c=Gc();__c<32||__c>126||__c==' ';)__c=Gc();
		for(;__c>31&&__c<127&&__c!=' ';++s,__c=Gc())*s=__c;*s=0;}
	template<class I>inline bool read(I&x){_eof=0;
		for(__f=1,__c=Gc();(__c<'0'||__c>'9')&&!_eof;__c=Gc()){if(__c=='-')__f=-1;_eof|=__c==EOF;}
		for(x=0;__c<='9'&&__c>='0'&&!_eof;__c=Gc())x=x*10+(__c&15),_eof|=__c==EOF;x*=__f;return!_eof;}
	template<class I>inline void write(I x){if(!x)pc('0');if(x<0)pc('-'),x=-x;
		while(x)qu[++qr]=x%10+'0',x/=10;while(qr)pc(qu[qr--]);}
	struct Flusher_{~Flusher_(){flush();}}io_flusher_;
}using io::pc;using io::gc;using io::pstr;using io::gstr;using io::read;using io::write;
const int N=2e6+5;
string str;
int t,n,m,s1,s2,len;
int a[N],b[N],c[N],bz[N],ans[N];
int main()
{
//	freopen("in.txt","r",stdin);
//	freopen("out.txt","w",stdout);
	ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	cin>>t;
	int sss=0;
	while(t--)
	{
		cin>>n>>m>>str,str=' '+str,sss++;
		if(n>m)swap(n,m);
		for(int i=1;i<=n+m;i++)ans[i]=0;
		for(int i=1;i<=n;i++)
		{
			s1=n,s2=m;int l=0;
			for(int j=1;j<=i;j++)a[s1--]=str[++l]-'0';
			b[s2--]=str[++l]-'0';
			while(l<n+m)
			{
				if(s1>s2)
				{
					while(s2&&str[l+1]=='0')b[s2--]=str[++l]-'0';
					a[s1--]=str[++l]-'0';
				}
				else
				{
					while(s1&&str[l+1]=='0')a[s1--]=str[++l]-'0';
					b[s2--]=str[++l]-'0';
				}
			}
			for(int j=1;j<=n+m;j++)c[j]=0;
			for(int j=1;j<=n;j++)c[j]+=a[j];
			for(int j=1;j<=m;j++)c[j]+=b[j];
			for(int j=1;j<=n+m;j++)if(c[j]>=2)c[j]-=2,c[j+1]++;
			int bz=0;
			for(int j=n+m;j>=1;j--)
			{
				if(c[j]>ans[j]){bz=1;break;}
				if(c[j]<ans[j])break;
			}
			if(bz)for(int j=1;j<=n+m;j++)ans[j]=c[j];
		}
		for(int i=1;i<=m;i++)
		{
			s1=n,s2=m;int l=0;
			for(int j=1;j<=i;j++)b[s2--]=str[++l]-'0';
			a[s1--]=str[++l]-'0';
			while(l<n+m)
			{
				if(s1>s2)
				{
					while(s2&&str[l+1]=='0')b[s2--]=str[++l]-'0';
					a[s1--]=str[++l]-'0';
				}
				else
				{
					while(s1&&str[l+1]=='0')a[s1--]=str[++l]-'0';
					b[s2--]=str[++l]-'0';
				}
			}
			for(int j=1;j<=n+m;j++)c[j]=0;
			for(int j=1;j<=n;j++)c[j]+=a[j];
			for(int j=1;j<=m;j++)c[j]+=b[j];
			for(int j=1;j<=n+m;j++)if(c[j]>=2)c[j]-=2,c[j+1]++;
			int bz=0;
			for(int j=n+m;j>=1;j--)
			{
				if(c[j]>ans[j]){bz=1;break;}
				if(c[j]<ans[j])break;
			}
			if(bz)for(int j=1;j<=n+m;j++)ans[j]=c[j];
		}
		int nd=-1;
		for(int i=n+m;i>=1;i--)if(ans[i]){nd=i;break;}
		if(nd==-1){cout<<"0\n";continue;}
		for(int i=nd;i>=1;i--)cout<<ans[i];
		cout<<"\n";
	}
}