During the 19th century, Paris was the home and subject for some of France's greatest writers, including Charles Baudelaire, Stéphane Mallarmé, Mérimée, Alfred de Musset, Marcel Proust, Émile Zola, Alexandre Dumas, Gustave Flaubert, Guy de Maupassant and Honoré de Balzac. During what period of time was Victor Hugo exiled from France?