var a : array[1..150] of integer;
    n, i, j, k, m, t, l : integer;
begin
  readln(n);
  for i := 1 to n  do begin
    readln(a[i]);
  end;
  for i := 1 to n do begin
    for j := 1 to n - i do begin
      if a[j] < a[j + 1] then begin
        t := a[j];
        a[j] := a[j + 1];
        a[j + 1] := t;
      end;
    end;
  end;
  i := 2;
  k := 1;
  while i <= n do begin

    if a[i] = a[i - 1] then begin
      inc(k);
    end
    else begin
    inc(m);
    if k >= 4 then begin
      inc(l);
    end;
    k := 1;
    end;

    inc(i);

  end;
  l := l + (k div 4);
  writeln(l);
end.

Why is WA?