#include <iostream>
using namespace std;
int main()
{
int t,a,b,c,z=1,tab[z];
cin>>t;
for(int i=0; i<t; i++)
{
cin>>a;
{
for(int j=0; j<a; j++)
{
cin>>b;
tab[z]=b;
z++;
}
z--;
c=z;
z=1;
for(int j=0; j<c; j++)
{
if(z%2==1)
{
z++;
}
else if(z%2==0)
{
cout<<tab[z];
z++;
}
}
z=1;
for(int j=0; j<c; j++)
{
if(z%2==1)
{
cout<<tab[z];
z++;
}
else if(z%2==0)
{
z++;
}
}
z=1;
}
}
return 0;
}
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