diff --git a/09_dynamic_programming/python/02_longest_common_substring.py b/09_dynamic_programming/python/02_longest_common_substring.py
index 0c27dae..7cf05f4 100644
--- a/09_dynamic_programming/python/02_longest_common_substring.py
+++ b/09_dynamic_programming/python/02_longest_common_substring.py
@@ -7,5 +7,7 @@ for i in range(0, len(dp_table_blue)):
     for j in range(0, len(dp_table_clues)):
         if dp_table_clues[j] == dp_table_blue[i]:
             dp_table[i][j] = dp_table[i-1][i-1] + 1
+        else:
+            dp_table[i][j] = 0
 
-print(dp_table)
\ No newline at end of file
+print(dp_table)