Add test cases with parenthesis

ans.txt

@@ -1,4 +1,7 @@
 3
 -1
 7
+9
 6
+0
+9

test.txt

@@ -1,6 +1,7 @@
-1+2
-=
+1+2=
 1-2=
-1+2*3
-=
+1+2*3=
+(1+2)*3=
 1+2+3=
+(1 - 1) + (2 - 2) =
+1 + 4 * 2 =