modified precedence of the merge operator in accordance to what is present in the original solution

acse/Acse.y

@@ -142,7 +142,7 @@ t_io_infos *file_infos;    /* input and output files used by the compiler */
 
 %left COMMA
 %left ASSIGN
-%left MERGE
+%nonassoc MERGE
 %left OROR
 %left ANDAND
 %left OR_OP