<form name="ejemplo1" action="datos.php" method="POST">
        <div class="etiqueta">Ingrese paises: </div>
                <div class="input_container">
                    <input autocomplete="off" type="text" id="pais_id" name="paises" onkeyup="autocompletar()" >
                    <ul id="lista_id"></ul>
                </div>
        <input type="submit" value="Enviar">
</form>