If you're into russian literature, likely the easiest entry point is "The Queen of Spades" by Alexander Pushkin, a lot of things written by Anton Chekhov like "The Death of a Government Clerk", Ivan Turgenev's "Fathers and Sons", etc

my favorite author is osamu dazai! I would definitely recommend the book no longer human, but read the warnings before you do if you are interested as it is pretty heavy!

For a few french books (and pretty much all of them are classics, they're all from the 19th or 20th century), I'd recommend the author Émile Zola, he wrote "Germinal", "Thérèse Raquin", "Au Bonheur des dames", Victor Hugo can be good too, there's the classic "Les misérables", "Notre-Dame de Paris" and "Quatrevingt-treize". There's also Jules Verne who's really good too, with "Le Tour du monde en quatre-vingts jours" and "Vingt Mille Lieues sous les mers". There's Albert Camus with "La Peste" and "L'étranger". I can recommend you to read a bit of Guy de Maupassant, the man is not too bad xD
It's a lot of recommendations but I hope you find one of them interesting ^^ ♥!!