Pascal/Turbo Pascal - encontrar el mayor, el menor y el mediano de una lista

{Mira esto a ver si te ayuda }

program listas;

 uses

    crt;

  const

      max = 21;

  var

    lista : array[1..max] of integer;

    mayor, menor, medio, n, num : integer;

  function existe(b : integer) : boolean;

  var

     k, s : integer;

  begin

      existe := false;

      for s := 1 to n - 1 do

      if lista[s] = b then

      existe := true;

  end;

  procedure carganumeros;

  begin

      n := 1;

    repeat

       num := random(max * 2) + 1;

       if existe(num) = false then

       begin

       lista[n] := num;

       n := n + 1;

       end;

    until n > max;

  end;

  procedure mayormenormedio;

  var

    temp, p, m : integer;

  begin

     for p := 1 to max do

       for m := max downto p + 1 do

       if lista[p] > lista[m] then

       begin

           temp := lista[p];

           lista[p] := lista[m];

           lista[m] := temp;

       end;

       mayor := lista[max];

       menor := lista[1];

       medio := lista[round(max / 2)];

  end;

  begin

      clrscr;

      randomize;

     carganumeros;

     writeln('  ***** Los Numeros Son *****');

     writeln;

     write('  ');

    for n := 1 to max do

    write(' ',lista[n]);

    mayormenormedio;

    writeln;

    writeln('   **** Los Valores Maximo Minimo Y Medio Son

****');

    writeln;

    writeln('  Maximo = ',mayor,'   Minimo = ',menor,'

Medio = ',medio);

    writeln;

    write('  ');

    for n := 1 to max do

    write(' ',lista[n]);

    readkey;

  end.