diff --git a/math/combinatorics.py b/math/combinatorics.py
deleted file mode 100644
index 57a0c46..0000000
--- a/math/combinatorics.py
+++ /dev/null
@@ -1,39 +0,0 @@
-from manim import *
-import random
-
-class Urn(Square):
-    def __init__(self):
-        Square.__init__(self, side_length=1.0, fill_color=GREY, fill_opacity=1.0)
-
-class Balls(VGroup):
-    colors = [BLUE, GREEN, YELLOW, PURPLE, RED, GRAY, MAROON, ORANGE, TEAL]
-
-    def __init__(self, n):
-        cols = Balls.colors
-        random.shuffle(cols)
-        cols = cols[:n]
-        super().__init__(*[LabeledDot(str(l), color=c) for l, c in zip(list(range(n)), cols)])
-
-class Main(Scene):
-    def construct(self):
-
-        urn = Urn().shift(3*LEFT)
-
-        n = 9
-        k = 6
-        balls = Balls(n)
-
-        left = list(range(n))
-        random.shuffle(left)
-        left = left[:k]
-        for d in left:
-
-            self.add(balls[d].move_to(urn), urn)
-            self.play(balls[d].animate.shift(DOWN))
-
-            self.play(urn.animate.shift(RIGHT))
-
-
-        self.wait(2)
-
-
diff --git a/segment_tree/segment_tree.py b/segment_tree/segment_tree.py
index 93610c2..cae3a91 100644
--- a/segment_tree/segment_tree.py
+++ b/segment_tree/segment_tree.py
@@ -1,6 +1,8 @@
 from manim import *
 
-class Main(Scene):
+import networkx as nx
+
+class Tree(Scene):
     def construct(self):
         n = 2**6
         l, r = 42, 59