diff --git a/Retos/ejercicio-recursividad.js b/Retos/ejercicio-recursividad.js
new file mode 100644
index 0000000..cf13687
--- /dev/null
+++ b/Retos/ejercicio-recursividad.js
@@ -0,0 +1,47 @@
+/**
+ * @author Dimacros
+ * 
+ * Problema:
+ * Las parejas de números que sumen 8; sin usar un loop.
+ * 
+ * Ejemplo: [3, 6, 2, -6, 10, -2, 0, 8, 4, 4]
+ * 
+ * return [ [ 6, 2 ], [ 10, -2 ], [ 0, 8 ], [4, 4] ]
+ */
+
+const numbers = [3, 6, 2, -6, 10, -2, 0, 8, 4, 4];
+
+function sumPairsEquals(total, numbers)
+{
+    const maxLenghtAllowed = 2;
+
+    if (numbers.length < maxLenghtAllowed) {
+        return accumulator();
+    }
+
+    [a, b, ...etc] = numbers;
+
+    if (a + b === total) {
+        accumulator().push([a, b]);
+    }
+
+    return sumPairsEquals(total, reduceLenght(numbers, 1));
+}
+
+function reduceLenght(numbers, length)
+{
+    return numbers.slice(length);
+}
+
+function accumulator()
+{
+    if( typeof accumulator.add === 'undefined' ) {
+        accumulator.add = [];
+    }
+
+    return accumulator.add;
+}
+
+console.log(
+    sumPairsEquals(8, numbers)
+);
diff --git a/Retos/sesion3-reto1/app/Album.js b/Retos/sesion3-reto1/app/Album.js
new file mode 100644
index 0000000..74d8cf8
--- /dev/null
+++ b/Retos/sesion3-reto1/app/Album.js
@@ -0,0 +1,12 @@
+class Album
+{
+    /**
+     * @param {String} title 
+     */
+    constructor(title)
+    {
+        this.title = title;
+    }
+}
+
+module.exports = Album;
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/app/Artist.js b/Retos/sesion3-reto1/app/Artist.js
new file mode 100644
index 0000000..7948437
--- /dev/null
+++ b/Retos/sesion3-reto1/app/Artist.js
@@ -0,0 +1,12 @@
+class Artist
+{
+    /**
+     * @param {String} name 
+     */
+    constructor(name)
+    {
+        this.name = name;
+    }
+}
+
+module.exports = Artist;
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/app/Factories/SongFactory.js b/Retos/sesion3-reto1/app/Factories/SongFactory.js
new file mode 100644
index 0000000..2cb9855
--- /dev/null
+++ b/Retos/sesion3-reto1/app/Factories/SongFactory.js
@@ -0,0 +1,16 @@
+const Artist = require("../Artist");
+const Album = require("../Album");
+const Song = require("../Song");
+
+class SongFactory
+{
+    create({artist: { name: artistName}, album: { title: albumTitle}, title, durationInSeconds})
+    {
+        const artist = new Artist(artistName);
+        const album = new Album(albumTitle);
+        
+        return new Song(artist, album, title, durationInSeconds);
+    }
+}
+
+module.exports = SongFactory;
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/app/Factories/UserFactory.js b/Retos/sesion3-reto1/app/Factories/UserFactory.js
new file mode 100644
index 0000000..1146300
--- /dev/null
+++ b/Retos/sesion3-reto1/app/Factories/UserFactory.js
@@ -0,0 +1,11 @@
+const User = require('../User');
+
+class UserFactory
+{
+    create(username)
+    {
+        return new User(username);
+    }
+}
+
+module.exports = UserFactory;
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/app/PlayList.js b/Retos/sesion3-reto1/app/PlayList.js
new file mode 100644
index 0000000..8b9b699
--- /dev/null
+++ b/Retos/sesion3-reto1/app/PlayList.js
@@ -0,0 +1,22 @@
+class PlayList
+{
+    /**
+     * @param {String} title 
+     */
+    constructor(title)
+    {
+        this.title = title;
+        this.songs = new Array;
+    }
+
+    /**
+     * 
+     * @param {Song} song 
+     */
+    addSong(song)
+    {
+        this.songs.push(song);
+    }
+}
+
+module.exports = PlayList;
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/app/Song.js b/Retos/sesion3-reto1/app/Song.js
new file mode 100644
index 0000000..e3d03d9
--- /dev/null
+++ b/Retos/sesion3-reto1/app/Song.js
@@ -0,0 +1,19 @@
+class Song
+{
+    /**
+     * 
+     * @param {Artist} artist 
+     * @param {Album} album 
+     * @param {String} title 
+     * @param {Number} durationInSeconds 
+     */
+    constructor(artist, album, title, durationInSeconds)
+    {
+        this.artist = artist;
+        this.album = album;
+        this.title = title;
+        this.durationInSeconds = durationInSeconds;
+    }
+}
+
+module.exports = Song;
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/app/User.js b/Retos/sesion3-reto1/app/User.js
new file mode 100644
index 0000000..2b05ec8
--- /dev/null
+++ b/Retos/sesion3-reto1/app/User.js
@@ -0,0 +1,36 @@
+const PlayList = require("./PlayList");
+
+class User
+{
+    /**
+     * @param {String} username 
+     */
+    constructor(username)
+    {
+        this.username = username;
+        this.playLists = new Array;
+    }
+
+    /**
+     * @param {String} title 
+     */
+    addPlayList(title)
+    {
+        this.playLists.push(new PlayList(title));
+    }
+
+    /**
+     * @param {String} title 
+     */
+    myPlayList(title)
+    {
+        return this.playLists.find(playList => playList.title === title);
+    }
+
+    myPlayLists()
+    {
+        return this.playLists;
+    }
+}
+
+module.exports = User;
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/bootstrap/app.js b/Retos/sesion3-reto1/bootstrap/app.js
new file mode 100644
index 0000000..728740b
--- /dev/null
+++ b/Retos/sesion3-reto1/bootstrap/app.js
@@ -0,0 +1,49 @@
+const SongFactory = require("../app/Factories/SongFactory");
+const UserFactory = require("../app/Factories/UserFactory");
+
+class Spotify
+{
+    /**
+     * @param {SongFactory} songFactory 
+     * @param {UserFactory} UserFactory 
+     */
+    constructor(songFactory, userFactory)
+    {
+        this.songFactory = songFactory;
+        this.userFactory = userFactory;
+        this.songs = new Array;
+        this.users = new Array;
+    }
+
+    createSong(song)
+    {
+        this.songs.push(this.songFactory.create(song));
+    }
+
+    createUser(username)
+    {
+        this.users.push(this.userFactory.create(username));
+    }
+
+    findUserByUsername(username)
+    {
+        return this.users.find(user => user.username === username);
+    }
+
+    findSongByTitle(title)
+    {
+        return this.songs.find(song => song.title === title);
+    }
+
+    allSongs()
+    {
+        return this.songs;
+    }
+
+    allUsers()
+    {
+        return this.users;
+    }
+}
+
+module.exports = new Spotify(new SongFactory, new UserFactory);
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/data.json b/Retos/sesion3-reto1/data.json
new file mode 100644
index 0000000..201bf72
--- /dev/null
+++ b/Retos/sesion3-reto1/data.json
@@ -0,0 +1,52 @@
+[
+    {
+        "artist": {
+            "name": "PXNDX"
+        },
+        "album": {
+            "title": "-"
+        },
+        "title": "Los Malaventurados lo lloran",
+        "durationInSeconds": 300
+    },
+    {
+        "artist": {
+            "name": "Tragokorto"
+        },
+        "album": {
+            "title": "¿A dónde vas?"
+        },
+        "title": "Borracho en el bar",
+        "durationInSeconds": 300
+    },
+    {
+        "artist": {
+            "name": "Los Violadores"
+        },
+        "album": {
+            "title": "-"
+        },
+        "title": "Sentimiento Fatal",
+        "durationInSeconds": 300
+    },
+    {
+        "artist": {
+            "name": ""
+        },
+        "album": {
+            "title": ""
+        },
+        "title": "",
+        "durationInSeconds": 300
+    },
+    {
+        "artist": {
+            "name": ""
+        },
+        "album": {
+            "title": ""
+        },
+        "title": "",
+        "durationInSeconds": 300
+    }
+]
\ No newline at end of file
diff --git a/Retos/sesion3-reto1/instrucciones.js b/Retos/sesion3-reto1/instrucciones.js
index 3e2793e..d74cc2d 100644
--- a/Retos/sesion3-reto1/instrucciones.js
+++ b/Retos/sesion3-reto1/instrucciones.js
@@ -10,50 +10,35 @@
  *
  * La cantidad y complejidad de las estructuras de datos es libre.
  *
- * */
+ */
 
-// Codigo Referencia
+const spotify = require('./bootstrap/app');
+const data = require('./data.json');
 
-class Autor {
-    constructor(nombre, pais) {
-        this.nombre = nombre;
-        this.pais = pais;
-    }
-}
+spotify.createUser('dimacros');
 
-class Cancion {
-    constructor(titulo, duracion, autor) {
-        this.titulo = titulo;
-        this.duracion = duracion;
-        this.autor = new Autor(autor.nombre, autor.pais);
-    }
-}
+data.forEach(song => {
+    spotify.createSong(song);
+});
 
-class db {
-    constructor(canciones) {
-        this.canciones = canciones;
-    }
-}
+const dimacros = spotify.findUserByUsername('dimacros');
 
-let SpotifyDB;
+dimacros.addPlayList('Rock');
+dimacros.addPlayList('Electro');
+dimacros.addPlayList('Salsa');
 
-function Spotify () {
-    return {
-        init: function () {
-            SpotifyDB = new db([]);
-        },
-        agregarCancion: function (titulo, duracion, autor) {
-            SpotifyDB.canciones.push(new Cancion(titulo, duracion, autor));
-        }
-    }
-}
+dimacros.myPlayList('Rock').addSong(
+    spotify.findSongByTitle('Los Malaventurados lo lloran')
+);
 
-let spotifyInstance = Spotify();
+dimacros.myPlayList('Rock').addSong(
+    spotify.findSongByTitle('Borracho en el bar')
+);
 
-spotifyInstance.init();
+dimacros.myPlayList('Rock').addSong(
+    spotify.findSongByTitle('Sentimiento Fatal')
+);
 
-spotifyInstance.agregarCancion('cancion uno', 4.3, {nombre: 'tanto', pais: 'tanto'});
-spotifyInstance.agregarCancion('cancion dos', 4.3, {nombre: 'tanto', pais: 'tanto'});
-
-
-console.log(SpotifyDB);
\ No newline at end of file
+console.log(
+    dimacros.myPlayList('Rock')
+);
\ No newline at end of file