MnRac

(ns untitled.core
  (:require [clojure.string :as str]))

(def file (slurp "/Users/mariano/Downloads/input.txt"))

(def room-names (str/split file #"\n"))

(def encrypted-names
  (map #(second (re-matches #"(.*)-[0-9]*\[.*\]$" %1)) room-names))