diff --git a/2024-1-15.py b/2024-1-15.py
index b048b97..a32a4c1 100644
--- a/2024-1-15.py
+++ b/2024-1-15.py
@@ -48,10 +48,70 @@ def p3():
 	return strings
 
 
+def valid():
+	alphabet = ['a', 'b']
+	strings = get_all_strings_with_a_given_alphabet_and_length(alphabet, 5)
+
+	def number_of_a_is_equal_to_3(s):
+		return s.count('a') == 3
+
+	def number_of_b_is_equal_to_3(s):
+		return s.count('b') == 3
+
+	# A game stops when a player has 3 a's or 3 b's, so there should be no trailing wins from the losing player
+	def valid_game(s):
+		if number_of_a_is_equal_to_3(s):
+			return not s.endswith('b')
+		elif number_of_b_is_equal_to_3(s):
+			return not s.endswith('a')
+
+	strings = list(filter(valid_game, strings))
+
+	return strings
+
+
+def p5():
+	alphabet = ['a', 'b']
+	valid_strings = valid()
+	strings = get_all_strings_with_a_given_alphabet_and_length(alphabet, 5)
+
+	def number_of_a_or_b_is_equal_to_3(s):
+		return s.count('a') == 3 or s.count('b') == 3
+
+	strings = list(filter(number_of_a_or_b_is_equal_to_3, strings))
+	strings = [i for i in strings if i not in valid_strings]  # strings - valid_strings
+	return strings
+
+
+def p6():
+	alphabet = ['a', 'b']
+	valid_strings = valid()
+	strings = get_all_strings_with_a_given_alphabet_and_length(alphabet, 5)
+
+	def number_of_a_is_equal_to_3(s):
+		return s.count('a') == 3
+
+	def number_of_b_is_equal_to_3(s):
+		return s.count('b') == 3
+
+	def opposite_number_of_winner_is_less_than_3(s):
+		if number_of_a_is_equal_to_3(s):
+			return s.count('b') < 3
+		elif number_of_b_is_equal_to_3(s):
+			return s.count('a') < 3
+
+	strings = list(filter(opposite_number_of_winner_is_less_than_3, strings))
+	strings = [i for i in strings if i not in valid_strings]  # strings - valid_strings
+	return strings
+
+
 def main():
 	print_strings(p1())
 	print_strings(p2())
 	print_strings(p3())
+	print_strings(valid())
+	print_strings(p5())
+	print_strings(p6())
 
 
 if __name__ == '__main__':
diff --git a/util.py b/util.py
index 86b171e..f114376 100644
--- a/util.py
+++ b/util.py
@@ -9,5 +9,15 @@ def get_all_strings_with_a_given_alphabet_and_length(alphabet, length):
 	return strings
 
 
+def replace_empty_string_with_symbol(strings):
+	symbol = 'ε'
+	for i in range(len(strings)):
+		if strings[i] == '':
+			strings[i] = symbol
+	return strings
+
+
 def print_strings(strings):
-	print(strings, len(strings))
+	strings = replace_empty_string_with_symbol(strings)
+	# print(len(strings))
+	print(strings)