{$mode objfpc}
uses stunit;
 var a:TAbstractStack;
begin
 a:=TMemoryStack.Create();
 a.pushInt(10);
 a.pushInt(20);
 a.pushInt(30);
 writeln(a.popInt());
 writeln(a.popInt());
 writeln(a.popInt());
 writeln(a.popInt()); 
 a.destroy;
end.