//on the name of Allah:)
#include<bits/stdc++.h>
#define int long long
#define Endl "\n"
#define pi 2 * acos(0.0)
#define mod 1000000007
#define Mul(a,b) (a%mod * b%mod)%mod
#define Add(a,b) (a%mod + b%mod)%mod
#define all(x) (x).begin(),(x).end()
#define allr(x) (x).rbegin(),(x).rend()
#define gcd(x, y) (__gcd(x, y))
#define lcm(x, y) ((x/gcd(x, y))*y)
#define faster cin.tie(NULL), cout.tie(NULL);
#define TC int t ; cin>>t ; for(int i=1;i<=t;i++)
const int N = 1e6 + 7;
using namespace std;
void s()
{
int n,k;
cin>>n>>k;
vector<string>v(n);
for(int i=0;i<n;i++)cin>>v[i];
vector<string>x;
int f=k;
int st=0;
int j=0;
for(int j=0;j<n-k;j++)
{ string res=v[j];
for(int i=j+1;i<n;i++)
{
res=res+v[i];
f--;
if(f==0)
{ x.push_back(res);
res=" ";
f=k;
st=i;
break;
}
}
}
if(x.size()==0)
{
cout<<v[0]<<endl;
return;
}
vector<int>ans;
for(int i=0;i<x.size();i++)ans.push_back(stoi(x[i]));
int mx=*max_element(all(ans));
cout<<mx<<endl;
}
int32_t main()
{
ios::sync_with_stdio(false);
//faster
TC
{
//cout<<"Case "<<i<<": ";
s();
}
}