public class Main {
  public static void main(String[] args) {
    // Take integer as input from stdin
    int q = new java.util.Scanner(System.in).nextInt();
   

    // Loop through the input
    for (int i = 0; i < q; i++) {
      // Take 2 integers as input from stdin
      int n = new java.util.Scanner(System.in).nextInt();
      int t = new java.util.Scanner(System.in).nextInt();

      // Create array and append input from stdin until newline
      int[] a = new java.util.Scanner(System.in).useDelimiter("\\n").next().chars().toArray();

      // Create array and append input from stdin until newline
      int[] b = new java.util.Scanner(System.in).useDelimiter("\\n").next().chars().toArray();

      // Print the arrays a and b
      System.out.println(a);
      return;
    }

    
  }
}