diff --git a/buggy.py b/buggy.py
--- a/buggy.py
+++ b/buggy.py
@@ -35,7 +35,7 @@
     trie.insert(S[i])
 
 for i in range(N):
-    l, r = 1, len(S[i]) + 1
+    l, r = 0, len(S[i]) + 1
     while r - l > 1:
         m = (l + r) // 2
         if trie.search(S[i][:m]) > 1:
