diff --git a/exam/packet.tex b/exam/packet.tex
index c2d415d..f5a198e 100644
--- a/exam/packet.tex
+++ b/exam/packet.tex
@@ -142,8 +142,8 @@ Output:
 \end{verbatim}
 
 % ========================= Problem 4 =========================
-\problem{Problem 3: Merge Intervals}
-\textit{Difficulty: Hard}
+\problem{Problem 4: Six Seven}
+\textit{Difficulty: Easy}
 \begin{itemize}
 You are given a string S composed of only the characters ‘6', ‘7’, ‘A', ‘B', and ‘\#' (without the quotation marks). This string is processed from left to right, and you must maintain a sequence of chracters that changes according to these rules: