program heap_test (output);

type fred = ^integer;
{     bigrek = record a, b, c, d : set of char end;}

var p1, p2, p3, p4, p5, p6, p7 : fred;

begin
  new (p1);
  new (p2);
  new (p3);
  new (p4);
  new (p5);
  new (p6);
  new (p7);
  writeln ('xxxxxxx');
  dispose (p2); writeln ('xxxxx_x fragmenting');
  dispose (p4); writeln ('xxx_x_x');
  dispose (p1); writeln ('xxx_x__ merge with lower block');
  dispose (p5); writeln ('xx__x__ merge with upper block');
  dispose (p3); writeln ('xx_____ merge above and below');
  dispose (p7); writeln ('_x_____ merge with main memory below');
  dispose (p6); writeln ('_______ merge this + upper block with main memory');
end.