diff -r 1f4e81950ab4 -r 8df654e9eb4e progs/comb1.scala
--- a/progs/comb1.scala	Mon Nov 14 15:50:42 2016 +0000
+++ b/progs/comb1.scala	Fri Dec 16 11:13:41 2016 +0000
@@ -92,14 +92,15 @@
 
 // arithmetic expressions
 lazy val E: Parser[String, Int] = 
-  (F ~ "*" ~ F) ==> { case ((x, y), z) => x * z } || F 
+  (T ~ "+" ~ E) ==> { case ((x, y), z) => x + z } ||
+  (T ~ "-" ~ E) ==> { case ((x, y), z) => x - z } || T 
+lazy val T: Parser[String, Int] = 
+  ((F ~ "*" ~ T) ==> { case ((x, y), z) => x * z } || F)
 lazy val F: Parser[String, Int] = 
-  ((T ~ "+" ~ T) ==> { case ((x, y), z) => x + z } ||
-   (T ~ "-" ~ T) ==> { case ((x, y), z) => x - z } || T)
-lazy val T: Parser[String, Int] = 
   ("(" ~ E ~ ")") ==> { case ((x, y), z) => y } || NumParser
 
-println(E.parse("1*2+3"))
+println(E.parse("4*2+3"))
+println(E.parse_all("4*2+3"))
 println(E.parse("1 + 2 * 3"))
 println(E.parse_all("(1+2)+3"))
 println(E.parse_all("1+2+3"))  // this is not parsed, because of