Program ex;
Var
  i, j, k, m, n, a, b, max:Integer;
  p : Char;
  Data:Array[1..1000] Of Integer;
Begin
  Readln(n);
  For i := 1 To n Do Begin
    Fillchar(Data, Sizeof(Data), 0);
    Max := 0;
    Readln(m);
    For j := 1 To m Do Begin
      Read(p);
      Readln(a, b);
      For k := a To b - 1 Do Inc(Data[k]);
      If b > Max Then Max := b;
    End;
    For j := 1 To Max Do Begin
      Case Data[j] OF
        1 : Write('A');
        2 : Write('B');
        3 : Write('C');
        4 : Write('D');
        5 : Write('E');
        6 : Write('F');
        7 : Write('G');
        8 : Write('H');
        9 : Write('I');
        10 : Write('J');
        11 : Write('K');
        12 : Write('L');
        13 : Write('M');
        14 : Write('N');
        15 : Write('O');
        16 : Write('P');
        17 : Write('Q');
        18 : Write('R');
        19 : Write('S');
        20 : Write('T');
        21 : Write('U');
        22 : Write('V');
        23 : Write('W');
        24 : Write('X');
        25 : Write('Y');
        26 : Write('Z');
      End;
    End;
    Writeln;
  End;
End.