A.cpp

/**************************************
 *
 * Author: Hadiur Rahman Nabil        *
 *
 **************************************/
#include <bits/stdc++.h>
using namespace std;

typedef long int li;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pi;
typedef pair<ll, ll> pll;

#define FAST                        \
  ios_base::sync_with_stdio(false); \
  cin.tie(NULL);                    \
  cout.tie(NULL);
#define pb push_back
#define mp make_pair
#define gcd(a, b) __gcd(a, b)
#define FOR(i, n) for (int i = 0; i < n; i++)
#define rep(i, k, n) for (int i = k; i < n; i++)
#define repp(i, k, n) for (int i = k; i <= n; i++)
#define endl "\n"

const int mod = 1e5 + 10;
const double PI = 3.1415926535897932384626;
const int mod_2 = 998244353;
const int MAX = 100005;
const double PII = 2.0 * acos(0.0);
/************************************************************************************************************************************************/

int main()
{
  FAST;

  int t;
  cin >> t;
  while (t--)
  {
    int n;
    string s;
    cin >> n >> s;
    char x = s[0];
    string a = "";
    for (int i = 1; i < n; i++)
    {
      if (s[i] == x)
      {
        a += s[i];
        if (i + 1 < n)
        {
          x = s[i + 1];
          i++;
        }
      }
    }
    cout << a << "\n";
  }
  return 0;
}