diff --git a/exam/ex.tex b/exam/ex.tex
index f586c92..d479167 100644
--- a/exam/ex.tex
+++ b/exam/ex.tex
@@ -359,7 +359,8 @@
       \unit[1522.125]{bytes}$. In total, the signature is
       $\unit[1554.125]{bytes}$ big.
 
-    \item \TODO
+    \item The signature can be made smaller if the underlying graphs have less
+      vertices. The signature shrinks linearly with the number of vertices.
 
   \end{enumerate}