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diff --git a/challenge-053/paulo-custodio/python/ch-2.py b/challenge-053/paulo-custodio/python/ch-2.py
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+#!/usr/bin/env python3
+
+# Challenge 053
+#
+# TASK #2
+# Vowel Strings
+# Write a script to accept an integer 1 <= N <= 5 that would print all possible
+# strings of size N formed by using only vowels (a, e, i, o, u).
+#
+# The string should follow the following rules:
+#
+# 'a' can only be followed by 'e' and 'i'.
+#
+# 'e' can only be followed by 'i'.
+#
+# 'i' can only be followed by 'a', 'e', 'o', and 'u'.
+#
+# 'o' can only be followed by 'a' and 'u'.
+#
+# 'u' can only be followed by 'o' and 'e'.
+#
+# For example, if the given integer N = 2 then script should print the following
+# strings:
+#
+# ae
+# ai
+# ei
+# ia
+# io
+# iu
+# ie
+# oa
+# ou
+# uo
+# ue
+
+import sys
+
+def show_vowels(n, string):
+    if len(string) == n:
+        print(string)
+    elif string == "":
+        for vowel in ['a', 'e', 'i', 'o', 'u']:
+            show_vowels(n, string+vowel)
+    elif string[-1] == 'a':
+        for vowel in ['e', 'i']:
+            show_vowels(n, string+vowel)
+    elif string[-1] == 'e':
+        for vowel in ['i']:
+            show_vowels(n, string+vowel)
+    elif string[-1] == 'i':
+        for vowel in ['a', 'e', 'o', 'u']:
+            show_vowels(n, string+vowel)
+    elif string[-1] == 'o':
+        for vowel in ['a', 'u']:
+            show_vowels(n, string+vowel)
+    elif string[-1] == 'u':
+        for vowel in ['e', 'o']:
+            show_vowels(n, string+vowel)
+    else:
+        print("expected vowel, got "+string)
+
+n = int(sys.argv[1])
+show_vowels(n, "")