Add make clean removed files.

yaukeywang · yaukeywang · commit 49f77a6e63df · 2017-03-19T20:13:26.000+08:00
diff --git a/makefile b/makefile
@@ -23,4 +23,4 @@ all: \
 	rm main.pdf main.ps2 link.ps2 link.pdf
 
 clean: 
-	rm *.jpg *.svg
+	rm -f *.jpg *.svg *.pdf *.png
