diff --git a/version0.16/version0.16.1/abstract_syntax_tree.h b/version0.16/version0.16.1/abstract_syntax_tree.h
index cf03b19..2c44cc3 100644
--- a/version0.16/version0.16.1/abstract_syntax_tree.h
+++ b/version0.16/version0.16.1/abstract_syntax_tree.h
@@ -31,11 +31,23 @@ class ast_tree_node
 		{
 			return type;
 		}
+		int return_line()
+		{
+			return line;
+		}
 		void add_child(ast_tree_node& new_child)
 		{
 			children.push_back(new_child);
 			return;
 		}
+		ast_tree_node& return_last_child()
+		{
+			std::list<ast_tree_node>::iterator i;
+			for(i=children.begin();i!=children.end();++i)
+				;
+			--i;
+			return *i;
+		}
 		void clear_tree()
 		{
 			line=0;
@@ -60,24 +72,24 @@ class ast_tree_node
 				std::cout<<" ";
 			if(type==__number)
 			{
-				std::cout<<"[";
+				std::cout<<"[ number:";
 				if(num==0 && fnum!=0)
 					std::cout<<fnum;
 				else if(num!=0 && fnum==0)
 					std::cout<<num;
 				else
 					std::cout<<0;
-				std::cout<<"]"<<std::endl;
+				std::cout<<" ]"<<std::endl;
 				return;
 			}
 			else if(type==__string)
 			{
-				std::cout<<"["<<str<<"]"<<std::endl;
+				std::cout<<"[ string:"<<str<<" ]"<<std::endl;
 				return;
 			}
-			std::cout<<"{[";
+			std::cout<<"{ [ node type:";
 			print_token(type);
-			std::cout<<"]"<<std::endl;
+			std::cout<<" ]"<<std::endl;
 			for(std::list<ast_tree_node>::iterator i=children.begin();i!=children.end();++i)
 				i->print(tab_num+1);
 			for(int i=0;i<tab_num;++i)
diff --git a/version0.16/version0.16.1/ast_generator.h b/version0.16/version0.16.1/ast_generator.h
index dd9a44e..0dd99aa 100644
--- a/version0.16/version0.16.1/ast_generator.h
+++ b/version0.16/version0.16.1/ast_generator.h
@@ -29,6 +29,13 @@ class ast_generator
 				node_cache.top().add_child(t);
 				return true;
 			}
+			else if((type==__add_operator || type==__sub_operator || type==__link_operator)
+					&& (node_cache.top().return_last_child().return_type()==__mul_operator || node_cache.top().return_last_child().return_type()==__div_operator)
+					&& node_cache.top().return_last_child().child_num()<2)
+			{
+				node_cache.top().return_last_child().add_child(t);
+				return true;
+			}
 			else
 			{
 				node_cache.push(t);
@@ -56,6 +63,13 @@ class ast_generator
 				node_cache.top().add_child(t);
 				return true;
 			}
+			else if((type==__add_operator || type==__sub_operator || type==__link_operator)
+					&& (node_cache.top().return_last_child().return_type()==__mul_operator || node_cache.top().return_last_child().return_type()==__div_operator)
+					&& node_cache.top().return_last_child().child_num()<2)
+			{
+				node_cache.top().return_last_child().add_child(t);
+				return true;
+			}
 			else
 			{
 				node_cache.push(t);
@@ -94,7 +108,27 @@ class ast_generator
 				node_cache.push(t);
 				return true;
 			}
-			else if(cache_top_type==__add_operator || cache_top_type==__sub_operator || cache_top_type==__mul_operator || cache_top_type==__div_operator || cache_top_type==__link_operator)
+			else if(cache_top_type==__add_operator || cache_top_type==__sub_operator || cache_top_type==__link_operator)
+			{
+				if(parse.top().type==__add_operator || parse.top().type==__sub_operator || parse.top().type==__link_operator)
+				{
+					t.add_child(node_cache.top());
+					node_cache.pop();
+					node_cache.push(t);
+				}
+				else if(parse.top().type==__mul_operator || parse.top().type==__div_operator)
+				{
+					if(node_cache.top().return_last_child().child_num()<2)
+					{
+						std::cout<<">>[Error] parse error:missing number or string at line "<<node_cache.top().return_line()<<"."<<std::endl;
+						return false;
+					}
+					t.add_child(node_cache.top().return_last_child());
+					node_cache.top().return_last_child()=t;
+				}
+				return true;
+			}
+			else if((cache_top_type==__mul_operator || cache_top_type==__div_operator) && node_cache.top().child_num()<2)
 			{
 				t.add_child(node_cache.top());
 				node_cache.pop();
@@ -125,7 +159,7 @@ class ast_generator
 					case __mul_operator:is_correct=operator_expr_gen();break;
 					case __div_operator:is_correct=operator_expr_gen();break;
 					case __link_operator:is_correct=operator_expr_gen();break;
-					case __semi:is_correct=true;break;
+					case __semi:is_correct=true;root.add_child(node_cache.top());node_cache.pop();break;
 					default:
 						is_correct=false;
 						std::cout<<">>[Error] parse error in line "<<parse.top().line<<":";
@@ -150,6 +184,14 @@ class ast_generator
 			}
 			return;
 		}
+		void print_ast()
+		{
+			//if(can_run)
+				root.print(0);
+			//else
+			//	std::cout<<">>[Parse] Error(s) occurred,stop."<<std::endl;
+			return;
+		}
 		void run()
 		{
 			if(can_run)
diff --git a/version0.16/version0.16.1/main.cpp b/version0.16/version0.16.1/main.cpp
index ce212aa..0bfdcd8 100644
--- a/version0.16/version0.16.1/main.cpp
+++ b/version0.16/version0.16.1/main.cpp
@@ -7,7 +7,7 @@ int main()
 	ast_generator cod;
 	std::string command;
 	std::cout<<">> Nasal interpreter by ValKmjolnir"<<std::endl;
-	std::cout<<">> input [help] to find help."<<std::endl;
+	std::cout<<">> Input [help] to find help."<<std::endl;
 	while(1)
 	{
 		std::cout<<">> ";
@@ -60,7 +60,7 @@ int main()
 			pas.parse_process(lex.return_list());
 			cod.input_token_stack(pas.return_stack());
 			cod.gen_main_prog();
-//			cod.print_gen_tree();
+			cod.print_ast();
 		}
 		else if(command=="run")
 		{